Added menu button libraries

Couple of animating button libraries
Merge pull request #156 from balysv/master

Added menu button libraries
Merge pull request #157 from naghtarr/master

Added assertj-android testing helper library
Update free.yml
Merge pull request #158 from tttzof351/master

Update free.yml
Adding Cheddar for android to android-arsenal
SmartGattLib, ViewBadger, GPUImage, NumberPicker &c

Added SmartGattLib, View Badger, Android GPUImage, Android NumberPicker, Android CalendarView, Android Visualizer
Merge pull request #159 from aliHafizji/master

Adding Cheddar for android to android-arsenal
Move Cheddar project in demos.
Merge pull request #160 from kugland/patch-1

SmartGattLib, ViewBadger, GPUImage, NumberPicker &c
Add MaskableLayout to Layouts category
Add Painter library to new  category