add end date for aws instance reservations

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

@@ -23,7 +23,7 @@ module Fog
               @reserved_instance = {}
             when 'requestId'
               @response[name] = value
-            when 'start'
+            when 'start','end'
               @reserved_instance[name] = Time.parse(value)
             end
           end

tests/aws/requests/compute/instance_tests.rb

@@ -116,6 +116,7 @@ Shindo.tests('Fog::Compute[:aws] | instance requests', ['aws']) do
       'instanceType'        => String,
       'availabilityZone'    => String,
       'start'               => Time,
+      'end'                 => Time,
       'duration'            => Integer,
       'fixedPrice'          => Float,
       'usagePrice'          => Float,