Torch: only write to sysfs if not already on

- SGH-I437 (expressatt) only requires the flash device
  sysfs to be written to one time. When the Torch writes
  to it repeatedly, it causes the flash to cycle between
  highest and lowest brightness.

Change-Id: I41347bc28d625d9497b02ecc94c1e9252d94e4b2
Torch: Allow theming via theme chooser

PS3: Fix commit message

Change-Id: Ib90ddfd514719581af2cf96c3a125ad3a7772006