Introduce device owner API to disable the keyguard

Let the device owner disable the keyguard to achieve undisturbed single
use mode with multiple apps. Calling this API has no effect if a
password
has been set for the calling user.

Bug: 19533026
Change-Id: I6b726b7f36efb669359e9da4b7e3db1f8031dad5
5 files changed