Remove HEW and drop < Android 4.0 support

Also update all library dependencies and use the most recent support
library features.
Use AppCompat Theme and change everything accordingly

Also removed the deprecated tab handling in the ActionBar and replaced
it by PagerTabStrip.
Removed some last HEW leftovers

They must have been hiding somewhere when Android Studio searched
through the code ;)
Fixed search
Fixed default text color
Merge pull request #257 from d-sko/no_hew

Remove HEW
Fix relations group header padding

... because the text overlapped the open/close toggle graphic. Also
removed the indicator ImageView as it's not used.
Merge pull request #258 from d-sko/expandablelist_fix

Fix relations group header padding