ignore IDEA generated folders "out" and "gen-external-apklibs"
idea files
removed bitcoinj-0.8 library
changed android-maven-plugin version from 3.7.0 to 3.8.0
fixed imports and some other minor revisions to code

-> bitcoin to zetacoin
-> some package shifting (wallet package and net.discovery package)

other minor revisions
- Also some fixes to overwriting an abstract class method onScriptsAdded
- wrapped try/catch around SendCoinsOfflineTask.sendCoinsOffline