Settings: Add HeadsUp setting.

Change-Id: Ib7a59145843bedb16aacc87bf6d3c6da143e8d3e

Conflicts:
	res/values/cm_strings.xml
	res/xml/notification_drawer.xml
Apply IO scheduler settings to all storage devices

Some older devices have MTD partitions and an external SD card.
Until now, IO scheduler settings were only applied to mmcblk0 which is
the external sd in older devices or the internal storage in most new devices.

Newer devices can also have both internal & external sdcard
(mmcblk0 & mmcblk1) so we should cover both of them

This needs the necessary permissions in init.<ro.hardware>.rc
for any extra device-specific partitions. Example:
https://github.com/LegacyXperia/android_device_semc_msm7x30-common/commit/5e6df8d60f6590e560629b2affd6da5f6a166dec

Change-Id: I340b8bab645c2bdd39e06f90835629a1983873bd

Conflicts:
	src/com/android/settings/cyanogenmod/BootReceiver.java
	src/com/android/settings/cyanogenmod/IOScheduler.java