Separate style-check from the tests; update docs accordingly

Squashed commit of the following:

commit 0b77bcf4060b2f7fffb71caed1dd933594e9f21c
Author: Thomas Schank <DrTom@schank.ch>
Date:   Tue Dec 23 11:52:26 2014 +0100

    Update guides wrt separation of style-check from tests

commit a624642d9477d83cf032e94be9e31fc105a831e7
Author: Thomas Schank <DrTom@schank.ch>
Date:   Tue Dec 23 11:34:46 2014 +0100

    Separate style check

commit 75b29b414b3da7a8cad7b7fe7cae3c976b644513
Author: Thomas Schank <DrTom@schank.ch>
Date:   Tue Dec 23 11:06:36 2014 +0100

    Adjust readme

commit bc8950dc6446699967b04c63bd120576795f7938
Author: Thomas Schank <DrTom@schank.ch>
Date:   Tue Dec 23 10:55:55 2014 +0100

    Fix linting spec
Refactor my controller
Upgrade gems