Settings: Advanced low battery indicator options (1/2)

Based on a idea I saw on Liquid and from CR3C0 (thanks guys) which we
modified to an extended version
This commit introduces following new SlimBean modes to indicate low battery
     * 0 = show dialog + play sound (default)
     * 1 = fire notification + play sound
     * 2 = show dialog only
     * 3 = fire notification only
     * 4 = play sound only
     * 5 = none

Due that notification is a unique SlimBean feature some words on it. Notification
behaviour is the same as Pop-up. User can dismiss it manually or it is
dismissed automatically if charger is connected, click on notification opens
PowerUsageSummary. Also you get a status bar ticker message about the notification
and notification is always on first place of list. And last if vibration is enabled
notification vibrates.

Change-Id: I5f65c1f23a8f2a9790ca003be6a8ef09a06335c2
Custom clear recents button (2/2)
- Option to show/hide
- Option to choose which corner to place (top left, top right, bottom left, bottom right)

Thanks omnirom team
Original commit: https://github.com/omnirom/android_packages_apps_OmniGears/commit/89818412841d558057c2b906bc3fd78f3c9adf13

Change-Id: I740c26906527e7300e962129f3435b5b90b6b721