use framework function to reboot device when possible

* cleaned up code path for adb reboot into bootloader
* when rebooting from adb into adb/bootloader/recovery, use
  package manager reboot function when:
  1. device API level >= 18
  2. has adb root
  3. framework is running

Change-Id: I4fd9cbe4c45c14e3c57ca3094eb328218e1703e2
3 files changed