Remove requirement for unique gateway in route table

lib/puppet/type/ec2_vpc_routetable.rb

@@ -47,9 +47,7 @@ def insync?(is)
   validate do
     routes = self[:routes]
     if routes
-      uniq_gateways = Array(routes).collect { |route| route['gateway'] }.uniq
       uniq_blocks = Array(routes).collect { |route| route['destination_cidr_block'] }.uniq
-      fail 'Only one route per gateway allowed' unless uniq_gateways.size == Array(routes).size
       fail 'destination_cidr_block must be unique' unless uniq_blocks.size == Array(routes).size
     end
   end