Upgrade versionCode to 7 and versionName to 3.4 (prepare to release)

Merge remote-tracking branch 'origin/master'

Version 6 (3.2)

Merge remote-tracking branch 'origin/master'

Change version code from 2 -> 3 -> 4, remove <uses-permission android…

…:name="com.google.android.gms.permission.AD_ID"/>

Merge remote-tracking branch 'origin/master'

Update .gitignore