Active Display: Fix pimp up (1/2)

This is a fix for the new features added with change: https://gerrit.omnirom.org/#/c/2819/

1. Fix the bug when Pocket mode is set to Notifications only and you
unlock your device with power key and if you put your hands over
proximity sensor the device will turn off (very annoying). The problem
was that mWakedByPocketMode it was put in wrong place.

2. Added an option in active display settings for "turn off display if
device gets pocketed again" (it's annoying for me, because i cover
the proximity very often).

3. Added an option in active display settings for proximity threshold.
I use this active display feature as an replacement for "sweep2wake",
and when my phone it's on the table, i just want to pass my hand over
it to show me the clock or notification (this was ok before the pimp up
commit), and now, you can choose how many seconds for proximity
threshold.

Practicaly, this commit fix one bug, and add settings for the
features added in 'pimp up' commit.

[2/2] part: https://gerrit.omnirom.org/#/c/3381/

Change-Id: I9e49ddb89002699714dcc3b3d2b1df87dc4bab4b