Squashed commit of the following:

commit d56e9628b870f18bf4d06f2b42f2fb325cfbfa93
Author: michael starke <michael.starke@hicknhack-software.com>
Date:   Mon Aug 25 20:01:02 2014 +0200

    Implemented settings for forced and recommendet key change intervals.

commit 64336eb662cf66173ef96657cec96b69a706f723
Author: michael starke <michael.starke@hicknhack-software.com>
Date:   Mon Aug 25 18:18:59 2014 +0200

    Added sanity checks for delay

commit 37087da84c2c2d12197196f0d15a517419dbad93
Author: michael starke <michael.starke@hicknhack-software.com>
Date:   Mon Aug 25 14:20:59 2014 +0200

    Added key change ui to database settings