helpers: add doesExist() helper

Returns true if the a file exists from a given path.
Switching to this new helper where possible.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
service: prepare perapp for android L

At and above android L getRunningTasks() will be
deprecated due to androids new document focused UI.
Since it will only return some sort of pseudo-data
per app profiles become useless.

But we are smarter than google and check for all apps
which are flagged with the IMPORTANCE_FOREGROUND flag.
Since the actual visible app is the first one in that
list, take it.

Since L is not officially released, we might want to
check this later again.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>
res: big UI overhaul

Change Aero Controls theme from RedHolo to
something more mature in preparation for android
L. This adds tons of new icons as well as some
improved layouts.

In general the res/ folder got a big cleanup.

Signed-off-by: Blechd0se <alex.christ@hotmail.de>