Add spinner option in order to create user variable directly via setVariable brick
Added delete updated, when user variables are deleted
adapted changeVariableBrick like setVariableBrick, added changeVariableBrick test
extended changeUserVariable test
extended changeUserVariable test, extended setUserVariable test
extended changeUserVariable test, extended setUserVariable test
Fixed unregister broadCast listener
Fixed changeVariableBrick
merge with master
Fixed brick update error
removed not used strings
Merge pull request #265 from Catrobat/UserVariablesSpinnerFix

Fixed issues: #252(Priority-Critical) and #246(Priority-High)