Fix PRNGFixes to work with SELinux enforce mode

makes /dev/urandom not writable on some devices
made vibration after unlocking cacheword optional

default is true meaning it will vibrate

fixes #2004
major overhaul in connection state tracking

Tracking the connection state of an activity to the cacheword service involves
several nuances that we were blundering over before. These changes implement
better state handling in these various corner cases.
clients unregister their BroadcastReceiver when disconnecting from CW

fixes #1897
add vibration feature to docs
provide two Handler constructors for convenience
add updated support lib
a few sample tweaks

* add vibrate permission to the sample
* some formatting
README: add minimum version
README: add ant documentation
clarify the consequence of clicking the notification

Explicitly state that that tapping the notification will lock the app.

refs #1789
implement custom notification intents

I took the opportunity to refactor the settings into a separate class.

refs #2424
add more docs about CacheWordHandler and the new settings configuration