Bumped MozStumbler to v1.5.2

This is a simultaneous github, fdroid and playstore release.
Fixes one crash from v1.5.1 related to Cyanogenmod.
Merge branch 'master' into 'master'

bump Mozilla Stumbler to 1.5.2

This is the first simultaneous release of Mozilla Stumbler across F-Droid, Github and the google playstore.

It includes one crash fix from the v1.5.1 release related to Cyanogenmod 11.

See merge request !375
Mon Escarcelle: Enable build.