Issue155 tool arrows zoom

Jenkins test pending
     [exec] org.catrobat.paintroid.test.integration.ActivityOpenedFromPocketCodeTest:INSTRUMENTATION_RESULT: shortMsg=java.lang.NullPointerException
     [exec] INSTRUMENTATION_RESULT: longMsg=java.lang.NullPointerException: Binary XML file line #27: Error inflating class org.catrobat.paintroid.ui.button.ColorButton
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