support pre JELLY_BEAN ndef
be more OO
Merge pull request #620 from emdete/p0

P0
added missing return statement. fixed api bug
made qr code available from muc and contact details as well
implement "correct" ndef parsing
optimize code abit
Merge pull request #622 from emdete/p1

P1
register nfc callback in every activity that provides a proper sharable uri
show avatar in editaccount
Make linter ignore properly checked API mismatch
Merge pull request #625 from SamWhited/linterfix

Make linter ignore properly checked API mismatch
clear avatar cache after nick name change
Add about dialog with license info
Move AboutDialog to correct path
Use real copyright symbol ©
Convert about dialog to activity
link to account details when touching own avatar
Make links clickable in about text
Use normal text size and color