Test against ruby2.0 in travis-ci
Merge pull request #335 from sanemat/feature/ruby-2-0

Test against ruby2.0 in travis-ci
Add support for different environment arguments than RAILS_ENV
Renamed :env_argument to :environment_variable
Renamed option in tests
Merge pull request #340 from andfx/env-argument

Add support for different environment variables other than RAILS_ENV
patch for rails 4
change method name: Whenever.rails4? -> Whenever.rails_binstub?
drying up setup.rb