Merge latest nfcd code

1. [Add formatNdef API] This API is not yet tested and used. Only implement the library code
2. [Add NDEF_WRITABLE technology] Add it according to GONK Spec
3. [Prevent double enable/disable] Do not do enable/disable multiple times when it is already in that state
4. [Fix enable NFC crash : do not enter low power mode just after enabling] This is a temporarily solution for this bug. It will be fix in https://bugzilla.mozilla.org/show_bug.cgi?id=934835
5. Refine code
6. Update NdefDetail structure according to GONK protocol spc change