Fix security issue: use ActionPack v4.1.7

**As a** developer 
**In order to**  ensure _Simple Token Authentication_ runs with fully-patched dependencies 
**I want** it to be tested with ActionPack v4.1.7 (see http://seclists.org/oss-sec/2014/q4/474)
**And** to be tested against v3.4.1 of Devise

**In order to** get the best from development tools 
**I want** to use Inch v0.5.5 

Thanks to [Gemnasium](https://gemnasium.com/gonzalo-bulnes/simple_token_authentication) for keeping an eye on dependencies ; )