(RE-2222) Push gems to internal server on release

This commit adjusts the ship_gem utility to include a try for pushing
the completed gem to the stickler host, currently rubygems.delivery.puppetlabs.net.
The host name can be overwritten using the environment variable GEM_HOST.
If it fails it puts an error for user to check if they can access the server and have stickler installed.
/home/erictimmerman/Desktop/kwalify-0.7.2.gem -> /usr/lib64/ruby/gems/1.8/gems/stickler-2.4.1/lib/stickler/repository/remote.rb:87:in `push': undefined method `response' for #<Excon::Errors::SocketError:0x7fdda1aa2dd8> (NoMethodError)
	from /usr/lib64/ruby/gems/1.8/gems/stickler-2.4.1/lib/stickler/client/push.rb:39:in `run'
	from /usr/lib64/ruby/gems/1.8/gems/stickler-2.4.1/lib/stickler/client/push.rb:35:in `each'
	from /usr/lib64/ruby/gems/1.8/gems/stickler-2.4.1/lib/stickler/client/push.rb:35:in `run'
	from /usr/lib64/ruby/gems/1.8/gems/stickler-2.4.1/bin/stickler:47
	from /usr/bin/stickler:23:in `load'
	from /usr/bin/stickler:23

Here's an example output if the host can't be resolved, it doesn't seem particularly helpful.