(TextView) failsafeView can now be written to.
Prearm failures are reported in red
Implemented watchdog to remove failsafe warnings after 2 seconds
Read arming failures out loud.
Read PreArm failures also
updated google play store link in readme
Merge pull request #922 from squilter/arm_fail_messages

Arm fail messages
Merge pull request #923 from squilter/fix-readme

updated google play store link in readme
fixes issue #911
added backward compatibility check.
Merge pull request #924 from ne0fhyk/fix_issue_911

Fixes issue #911
Merge https://github.com/DroidPlanner/droidplanner