Implemented NFC Quick Settings tile

[MohammadAG]

It works!!! It works I tell you! I use ServiceManager.getService("nfc") and check if it's null, only if it isn't should NfcAdapter.getDefaultAdapter be called.

Cherry picked commits aren't exactly my specialty, though I assume this should merge cleanly and work as is :)

[C3C0]

Great job! Please, note that the official repo for GB is now at https://github.com/GravityBox/GravityBox There are 2 branches: one for jellybean and one for kitkat. You should send pull request against the jellybean branch.

Btw, in KitKat branch, I already implemented NFC tile using slightly different aproach regarding NfcAdapter availability. Here's the commit: https://github.com/GravityBox/GravityBox/commit/8909b727e09fe6ed8b24ba13672e184543f291fd