Implemented new About Dialog

Added ok button and bottom separator
Adapted to new design
Modified AboutDialogTest
layout changes

changed to relative layout
sp instead of dp for text
removed padding according to mockup
test changed
adjusted paddings
changed asserttrue to assertfalse
adapted license text line
autoformat layout xml file
Merge pull request #175 from Catrobat/AboutDialog

Implemented new About Dialog
Merge branch 'master' into issue#105