DC: add API with sample

apps which want to make use of the API need permission to use it.
permission: org.namelessrom.devicecontrol.API

Sample app is included, just import the top level settings.gradle,
ensure DeviceControl is installed (or not, the sample knows about it) and
run the sample.

Change-Id: I984c90b7a54e03b05ca1ac4a5d1aeda61c8b00e7