Rescue opennebula loading issues

`require "opennebula"` fails when downstream tries to require `xmlrpc`
which is not included within the main `fog` dependencies.

The problem is that the `LoadError` was being trapped by
`Fog::SevicesMixin#new` so it was reporting that the OpenNebula provider
did not offer the service.

This then handles the `Fog::Errors::LoadError` in all the shindo tests
that halted the run. These tests will be pending unless `opennebula` is
installed.

lib/fog/opennebula/compute.rb

@@ -98,7 +98,12 @@ module Fog
           @opennebula_endpoint = options[:opennebula_endpoint]
           @opennebula_username = options[:opennebula_username]
           @opennebula_password = options[:opennebula_password]
-          require 'opennebula'
+
+          begin
+            require "opennebula"
+          rescue LoadError
+            raise Fog::Errors::LoadError, "To use OpenNebula provider, you must load 'opennebula' gem"
+          end
         end
 
         def client

lib/fog/opennebula/requests/compute/OpenNebulaVNC.rb

@@ -20,7 +20,11 @@
 
 require 'rubygems'
 require 'json'
-require 'opennebula'
+begin
+  require "opennebula"
+rescue LoadError
+  raise Fog::Errors::LoadError, "To use OpenNebula provider, you must load 'opennebula' gem"
+end
 
 
 #if !ONE_LOCATION

tests/opennebula/compute_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests('Fog::Compute[:opennebula]', ['opennebula']) do
-
-  compute = Fog::Compute[:opennebula]
+  begin
+    compute = Fog::Compute[:opennebula]
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
   tests("Compute collections") do
     %w{networks groups}.each do |collection|

tests/opennebula/models/compute/flavor_tests.rb

@@ -1,6 +1,10 @@
 Shindo.tests('Fog::Compute[:opennebula] | flavor model', ['opennebula']) do
+  begin
+    flavors = Fog::Compute[:opennebula].flavors
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
-  flavors = Fog::Compute[:opennebula].flavors
   flavor = flavors.get_by_name('fogtest').last
 
   tests('The flavor model should') do

tests/opennebula/models/compute/flavors_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests('Fog::Compute[:opennebula] | flavors collection', ['opennebula']) do
-
-  flavors = Fog::Compute[:opennebula].flavors
+  begin
+    flavors = Fog::Compute[:opennebula].flavors
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
   tests('The flavors collection should') do
     test('should be a kind of Fog::Compute::OpenNebula::Flavors') { flavors.kind_of? Fog::Compute::OpenNebula::Flavors }

tests/opennebula/models/compute/group_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests('Fog::Compute[:opennebula] | group model', ['opennebula']) do
-
-  groups = Fog::Compute[:opennebula].groups
+  begin
+    groups = Fog::Compute[:opennebula].groups
+  rescue Fog::Errors::LoadError
+    pending
+  end
   group = groups.last
 
   tests('The group model should') do

tests/opennebula/models/compute/groups_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests('Fog::Compute[:opennebula] | groups collection', ['opennebula']) do
-
-  groups = Fog::Compute[:opennebula].groups
+  begin
+    groups = Fog::Compute[:opennebula].groups
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
   tests('The groups collection') do
     test('should be a kind of Fog::Compute::OpenNebula::Groups') { groups.kind_of? Fog::Compute::OpenNebula::Groups }

tests/opennebula/models/compute/network_tests.rb

@@ -1,6 +1,10 @@
 Shindo.tests('Fog::Compute[:opennebula] | network model', ['opennebula']) do
+  begin
+    networks = Fog::Compute[:opennebula].networks
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
-  networks = Fog::Compute[:opennebula].networks
   network = networks.get_by_name('fogtest')
 
   tests('The network model should') do

tests/opennebula/models/compute/networks_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests('Fog::Compute[:opennebula] | networks collection', ['opennebula']) do
-
-  networks = Fog::Compute[:opennebula].networks
+  begin
+    networks = Fog::Compute[:opennebula].networks
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
   tests('The networks collection') do
     test('should be a kind of Fog::Compute::OpenNebula::Networks') { networks.kind_of? Fog::Compute::OpenNebula::Networks }

tests/opennebula/requests/compute/vm_allocate_tests.rb

@@ -1,6 +1,10 @@
 Shindo.tests("Fog::Compute[:opennebula] | vm_create and vm_destroy request", 'opennebula') do
+  begin
+    compute = Fog::Compute[:opennebula]
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
-  compute = Fog::Compute[:opennebula]
   name_base = Time.now.to_i
   f = compute.flavors.get_by_name("fogtest")
 

tests/opennebula/requests/compute/vm_suspend_resume_tests.rb

@@ -1,6 +1,9 @@
 Shindo.tests("Fog::Compute[:opennebula] | vm_suspend and vm_resume request", 'opennebula') do
-
-  compute = Fog::Compute[:opennebula]
+  begin
+    compute = Fog::Compute[:opennebula]
+  rescue Fog::Errors::LoadError
+    pending
+  end
 
   name_base = Time.now.to_i
   f = compute.flavors.get_by_name("fogtest")