Settings: Add summary for launch music app when headset is connected

This commit adds a summary for the 'launch music app when headset is
connected' feature. I made this change because in some languages
(e.g. German) the title to descripe this feature got to long for
one line. That just looked aweful.

Before: http://goo.gl/TNDX7
After:  http://goo.gl/PYVme

Change-Id: I67d74e4df5824a8bfaf13dbe708cdef87fbe738c
Settings: Simplyfiy expanded desktop summary

There is no need to have an extra summary string to display the
state of the expanded desktop mode. This commit removes the unneeded
strings and uses the entries as summary.

Change-Id: Ia7e99ec52577c64d786ef5a0117fb33f5af671ab
Merge remote branch 'cm/cm-10.1'