Drop ipaddress dependency in favor of built in ipaddr

The ipaddr module is part of Ruby itself and can be used to check for
range inclusion.

fog-aws.gemspec

@@ -31,5 +31,4 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'fog-core',  '~> 2.1'
   spec.add_dependency 'fog-json',  '~> 1.1'
   spec.add_dependency 'fog-xml',   '~> 0.1'
-  spec.add_dependency 'ipaddress', '~> 0.8'
 end

lib/fog/aws/requests/compute/create_network_interface.rb

@@ -2,6 +2,7 @@ module Fog
   module AWS
     class Compute
       class Real
+        require 'ipaddr'
         require 'fog/aws/parsers/compute/create_network_interface'
 
         # Creates a network interface
@@ -68,7 +69,7 @@ module Fog
               raise Fog::AWS::Compute::Error.new("Unknown subnet '#{subnetId}' specified")
             else
               id = Fog::AWS::Mock.network_interface_id
-              cidr_block = IPAddress.parse(subnet['cidrBlock'])
+              cidr_block = IPAddr.new(subnet['cidrBlock'])
 
               groups = {}
               if options['GroupSet']
@@ -82,12 +83,14 @@ module Fog
               end
 
               if options['PrivateIpAddress'].nil?
+                range = cidr_block.to_range
                 # Here we try to act like a DHCP server and pick the first
                 # available IP (not including the first in the cidr block,
                 # which is typically reserved for the gateway).
-                cidr_block.each_host do |p_ip|
-                  unless self.data[:network_interfaces].map{ |ni, ni_conf| ni_conf['privateIpAddress'] }.include?p_ip.to_s ||
-                    cidr_block.first == p_ip
+                range = range.drop(2)[0..-2] if cidr_block.ipv4?
+
+                range.each do |p_ip|
+                  unless self.data[:network_interfaces].map{ |ni, ni_conf| ni_conf['privateIpAddress'] }.include?p_ip.to_s
                     options['PrivateIpAddress'] = p_ip.to_s
                     break
                   end

lib/fog/aws/requests/compute/create_subnet.rb

@@ -2,7 +2,7 @@ module Fog
   module AWS
     class Compute
       class Real
-        require 'ipaddress'
+        require 'ipaddr'
         require 'fog/aws/parsers/compute/create_subnet'
 
         # Creates a Subnet with the CIDR block you specify.
@@ -50,11 +50,11 @@ module Fog
               if vpc.nil?
                 raise Fog::AWS::Compute::NotFound.new("The vpc ID '#{vpcId}' does not exist")
               end
-              if ! ::IPAddress.parse(vpc['cidrBlock']).include?(::IPAddress.parse(cidrBlock))
+              if ! ::IPAddr.new(vpc['cidrBlock']).include?(::IPAddr.new(cidrBlock))
                 raise Fog::AWS::Compute::Error.new("Range => The CIDR '#{cidrBlock}' is invalid.")
               end
               self.data[:subnets].select{ |s| s['vpcId'] == vpcId }.each do |subnet|
-                if ::IPAddress.parse(subnet['cidrBlock']).include?(::IPAddress.parse(cidrBlock))
+                if ::IPAddr.new(subnet['cidrBlock']).include?(::IPAddr.new(cidrBlock))
                   raise Fog::AWS::Compute::Error.new("Conflict => The CIDR '#{cidrBlock}' conflicts with another subnet")
                 end
               end