Prevent "Unrecognized arguments: version" Fog warning when specifying region.version

[rafd123]

The :version argument is not recognized by the Fog::AWS::ELB service

[rtyler]

What version of fog are you using?

[rafd123]

I'm not sure the version of fog is relevant here since in all the history of fog-aws, as far as I can tell, did the constructor for the ELB service object ever include :version as one of the accepted constructor arguments: https://github.com/fog/fog-aws/blob/master/lib/fog/aws/elb.rb#L17

Compare this to the compute service object's accepted constructor arguments: https://github.com/fog/fog-aws/blob/master/lib/fog/aws/compute.rb#L7

Since vagrant-aws conflates the fog_config for both service objects, the :version argument should be excluded when instantiating the ELB service object for the same reason the other exclusions are in place in the event that the vagrant-aws user specifies the version on the region_config in their Vagrantfile (which may be necessary when using a private cloud solution that has an EC2 API façade sitting in front of it).