"Clear all" button on recent apps

    Ported from ParanoidAndroid by zigackly:
    https://github.com/ParanoidAndroid/android_frameworks_base/commit/f8c44e6ef667a3ebe9b658f148fa78a8d4f9a8dd

    Add button to tablet layout ported from Codename Android by zigackly:
    https://github.com/CNA/android_frameworks_base/commit/8d259fe3588c261baa5a17c361255cf28cc82bfe

    Patch set 2: Make the layout consistent, with the button at the top right.

    Patch set 3: Remove the redundant use of removeTask()

    Patch set 4: Top right layout does not work in tablet mode: make it top left for tablets only.

    Patch set 5: Different implementation (No need to keep track of views) - Danesh M

    Patch set 6: Top left layout no longer works for tablet mode with new implementation.
                 Make it bottom left for tablets only.
Highlight the clear button in the recents view when clicked

This commit also makes copies of the ic_notify drawables for the recents
panel to avoid any collisions with possible future changes to the
notification bar UI. (The pressed state drawable was already an unused
leftover resource).

Change-Id: Ib0d5982e80771b6639efd25ac792ebfe9f1ca1c5