Fix ActiveRecord::ConnectionNotEstablished error in tests.
Fixes alexrothenberg/ammeter#30
Remove hard dependency to beta version of rspec
Add rails_helper to tests.
Fixes "Don't know how to build task 'test:prepare'" error
Merge pull request #30 from d4rky-pl/master

Compatilibilty with Rails 4 (but tests are failing for rspec 2.x)

Thx @d4rky-pl