Upon accepting a video call on a device that can not establish a video track on
its own (for example by not having a camera), displaying the video enable/disable
button would fail. This commit defaults this button to disabled.

OkHttp gives us more fine grained control over the HTTP library and frees us from any platform bugs

this new behaviour still takes care of not going online when quickly
checking for the time but it also includes systems that don’t have a
lock screen or incorrectly report being unlocked.

* mission statement is now hosted on https://gultsch.de
* XEPs.md has been replaced by conversations.doap
* observations.md is just outdated and boring by now