Minor refactor tidy up TokenAuthenticationHandler

Fix circular dependency (!)
Minor fix harmless variables shadowing in dynamically defined methods

Remove forgotten hack related to the deprecated Cucumber scenarios
See #104
Require ActiveRecord as development dependency

Fix Travis CI build, force `--no-deployment` installation

As long as an ORM/ODM/OxM is available, there should be
no obligation to install ActiveRecord.

About the Travis issue, see:
https://github.com/gonzalo-bulnes/simple_token_authentication/ \
commit/5c04e13c44379d95b95c1affcdb85177cf6188e3 and
https://stackoverflow.com/q/26221540/3767264