Settings: Port Lockscreen Targets and Shortcuts

    First thanks to PA and CM which gave us partly code and some ideas.
    Still some parts of the original implementation are/were buggy as well
    we needed to ehance it.

    Whatever the new Slim version is now ready and seems to be completly bug
    free.

    - Configurable lockscreen targets...on tablets 8 on phone either 5 or 8
    - configurable lockscreen shortcuts only on phones...up to 5 shortcuts
    - Centralazing some methods....using now then rounded corner on custom
      images systemwide...means on all other shorcut features we have
    - multiDpi compatible
    - new settings logic
    - instance handling of all dialogs like we do on all other places
      way nicer this way
    - tons of fixes

    thanks kroz for redoing all xxhdpi icon in fb

Change-Id: I74d4405e6eed0cd79baa32e3fd197bd36f3f3c8c
LockscreenShortcutFragment needs onPreferenceTreeClick
- Moved the option to onPrefrenceTreeClick method or the option won't stick and resets itself when we leaves the option screen

Change-Id: Id4f904ba34ab7a8617b4d90f4795fab89f4c4ee5