Try new android build environment on Travis CI

See https://github.com/travis-ci/travis-ci/issues/1395
start preparing version 0.4
add 0.3 features
mention origin of .utility/remove-incomplete-translations [skip ci]
Add badge with latest version [skip ci]
upgrade Android build-tools to 20.0.0
use Android SDK 23.0.2
use android build-tools 20.0.0 for gradle
add scripts to crop and scale screenshots
use variable for image file
get Imagesize
Translated using Weblate (Italian)

Currently translated at 100.0% (74 of 74 strings)
fix escaping apostroph
add newlines
Translated using Weblate (Italian)

Currently translated at 100.0% (74 of 74 strings)
Merge remote-tracking branch 'origin/master'
translated to Italian, thanks to Matteo Regazzi
add comments
detect image size and use different settings based on the result
Translated using Weblate (Spanish)

Currently translated at 21.6% (16 of 74 strings)