[1/2] base: Lockscreen Notifications

OmniGears: https://gerrit.omnirom.org/#/c/6062/

Modifications of OmniROM:
- Dynamic width control: Schubi <schubi@erlangen.ccc.de>
- Control whether notifications should be dismissed or not
& Force include apps with low priority notifications when
  hide low priority is enabled: Utkarsh Gupta <utkarsh.eminem@gmail.com>

Change-Id: Ifba54d3b8e3035e3cacedcb60c2691e325326e05