Add a reload() method to the vSphere service.

Like other compute services, it would be useful if vSphere also
supported reload(). The method should reestablish any session state
required for Fog when network errors arise (EPIPE, etc).

Fixes: #2307

lib/fog/vsphere/compute.rb

@@ -343,8 +343,35 @@ module Fog
           @vsphere_ssl      = options[:vsphere_ssl] || true
           @vsphere_expected_pubkey_hash = options[:vsphere_expected_pubkey_hash]
           @vsphere_must_reauthenticate = false
-
+          @vsphere_is_vcenter = nil
           @connection = nil
+          connect
+          negotiate_revision(options[:vsphere_rev])
+          authenticate
+        end
+
+        def reload
+          connect
+          # Check if the negotiation was ever run
+          if @vsphere_is_vcenter.nil?
+            negotiate
+          end
+          authenticate
+        end
+
+        private
+        def negotiate_revision(revision = nil)
+          # Negotiate the API revision
+          if not revision
+            rev = @connection.serviceContent.about.apiVersion
+            @connection.rev = [ rev, ENV['FOG_VSPHERE_REV'] || '4.1' ].min
+          end
+
+          @vsphere_is_vcenter = @connection.serviceContent.about.apiType == "VirtualCenter"
+          @vsphere_rev = @connection.rev
+        end
+
+        def connect
           # This is a state variable to allow digest validation of the SSL cert
           bad_cert = false
           loop do
@@ -366,21 +393,8 @@ module Fog
           if bad_cert then
             validate_ssl_connection
           end
-
-          # Negotiate the API revision
-          if not options[:vsphere_rev]
-            rev = @connection.serviceContent.about.apiVersion
-            @connection.rev = [ rev, ENV['FOG_VSPHERE_REV'] || '4.1' ].min
-          end
-
-          @vsphere_is_vcenter = @connection.serviceContent.about.apiType == "VirtualCenter"
-          @vsphere_rev = @connection.rev
-
-          authenticate
         end
 
-        private
-
         def authenticate
           begin
             @connection.serviceContent.sessionManager.Login :userName => @vsphere_username,