Dropping cucumber features

* Mostly skeletons and dummies
* Not used and outdated
Dropping cucumber tasks from Rakefile
Moved devel deps to Gemfile
Dropping legacy AMQP support

* Not maintained
* No AMQP-capable server available
* Might return in the future as a separate gem
Updated rOCCI-core to 4.2.0
Clean-up in the gemspec file

* Removed old references to cucumber features
Updated Keystone authN plugin

* Minor refactoring and clean-up
* Added support for `snf-auth`
* Fixes #15
Merge pull request #16 from arax/new_core

Staging for 4.2.0.beta.1