Add the ability to return the security group ID when requesting a SecurityGroupData object

lib/fog/aws/models/compute/security_group.rb

@@ -7,8 +7,8 @@ module Fog
       class SecurityGroup < Fog::Model
 
         identity  :name,            :aliases => 'groupName'
-
         attribute :description,     :aliases => 'groupDescription'
+        attribute :group_id,        :aliases => 'groupId'
         attribute :ip_permissions,  :aliases => 'ipPermissions'
         attribute :owner_id,        :aliases => 'ownerId'
 

lib/fog/aws/parsers/compute/describe_security_groups.rb

@@ -40,7 +40,7 @@ module Fog
               end
             when 'groups'
               @in_groups = false
-            when 'groupDescription', 'ownerId'
+            when 'groupDescription', 'ownerId', 'groupId'
               @security_group[name] = value
             when 'groupName'
               if @in_groups

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

@@ -16,6 +16,7 @@ module Fog
         #     * 'requestId'<~String> - Id of request
         #     * 'securityGroupInfo'<~Array>:
         #       * 'groupDescription'<~String> - Description of security group
+	#	* 'groupId'<~String> - ID of the security group.
         #       * 'groupName'<~String> - Name of security group
         #       * 'ipPermissions'<~Array>:
         #         * 'fromPort'<~Integer> - Start of port range (or -1 for ICMP wildcard)
@@ -59,6 +60,7 @@ module Fog
           aliases = {
             'description' => 'groupDescription',
             'group-name'  => 'groupName',
+            'group-id'    => 'groupId',
             'owner-id'    => 'ownerId'
           }
           permission_aliases = {