[2/2] Power connect/disconnect notification support

part 1/2: frameworks/base PowerUI and Settings
http://review.cyanogenmod.org/#/c/35241/

part 2/2: packages/apps/Settings Sound settings
http://review.cyanogenmod.org/#/c/35242/

patchset 3:
    set settings persistence and dependencies in xml resource file
    shrink long lines
    add the default notification tone to the ringtone picker and
        remove the now redundant "use default" checkbox
    move values/strings.xml content to the cyanogenmod section
    improve (mostly delete) wording in values/strings.xml
    remove tab whitespace

Change-Id: I7ddd8a47ae4f9a62c586023d151ac42bbe8424c7

Conflicts:
	res/values/strings.xml
	res/xml/sound_settings.xml
	src/com/android/settings/SoundSettings.java
Settings: fix storage measurement for device without emulated sdcard

StorageMeasurement: misc files should only be measured for internal
storage only if it is the emulated storage, otherwise misc count
for the primary storage will be erroneously duplicated on the
internal storage count.

StorageVolumePreferenceCategory:
  - Always create mMountTogglePreference to avoid null pointer
    exception for code that relies on it existing
  - Check if the keys exist before calculating totalValues to
    avoid null pointer exception on storage where media is not
    calculated
  - For available/readonly, set title, not summary (summary is
    supposed to be the amount available)

Change-Id: Ib217f79ee562dffc514696fff038e58ed0dba7d9