MUS-82: GridLayout Positioning
MUS-82: Strings added
Merge branch 'MUS-82_CreateDrumKit' of https://github.com/Catrobat/musicdroid into MUS-82_CreateDrumKit

Conflicts:
	MusicdriodNew/Musicdroid/res/menu/drum_menu.xml
	MusicdriodNew/Musicdroid/res/values/strings.xml