QRSA OTP Authentication

Aug 31, 2017

1.4:
- Added Md5 hash verification, to further protect against malleability attacks.
1.3:
- Improved code so the app can more reliable kill itself.
1.2:
- Added OTP into @string/app_name to match Google Play app name.
1.1:
- Changed enroll function to exclude linebreaks in the public key.
- Added new "u" enroll function. Read the description or GitHub page for more information. The "u" enroll function is recommended when enrolling from a computer.