add rake to kitchen  Gemfile
add rake cloud:vm:deregister task
deregister VM before terminating
deregister VM via rake task
fix credentials constant
call read on Credentials class
clean up Rakefile
Merge pull request #48 from SUSE/review_140410_add_deregister_rake_task_and_fix_suseconnect_jenkins_node

[Review] Request from 'vlewin' @ 'SUSE/connect/review_140410_add_deregister_rake_task_and_fix_suseconnect_jenkins_node'
increase aruba timeout
Enforce single quotes in credentials spec
Move fixtures_dir into appropriate helper
Refactor credentials spec
Move authority of credentials to respective class
Cutoff uuid
Use included class
Drop trailing empty line
Remove uuid part - as generation of login is on server
Cleanup logger
Bump version to 13
Refactor credentials class