Load Deploy Config with *.erb Extension if Exists

[rience]

At the moment configuration is by default loaded from deploy.yml file. It's the evaluated using ERB. But that means that IDE won't pick up ERB dialect. It'd be great if you could create deploy.yml.erb file and do not have to pass path to this file using -c flag.

So this PR is adding two things

1. If configuration file with "erb" extension exists - it'll be loaded instead
   • For example if deploy.yml.erb exists - it'll be loaded instead of deploy.yml
   • If custom config custom_deploy.yml.erb exists - it'll also be loaded instead of custom_deploy.yml (Note: this will also happens when you specify -c custom_deploy.yml)
2. It's also changing one of fixtures from deploy.erb.yml to depoy.yml.erb since I think this should be default naming for template file (just like in Rails you have *.html.erb)

[rience]

Closing this as #391 is I think better solution than this since it honours "destination" setting.