n7100: Read me & clean up

  PS2: Add README & revert fingerprint to the previous listed.
  PS3: ro.product.device is actually set with TARGET_DEVICE & not
       PRODUCT_DEVICE; this has been corrected.
  PS4: PRODUCT_RELEASE_NAME isn't used in omnirom.

Change-Id: Icba3cab87601342d0ca71af8c33a8299bed91dbc
Merge "n7100: Read me & clean up" into android-4.4