removed interfaces, introduced PaintroidImage class,
Merge branch 'master' into 8.78_FileIO
refactor PaintroidApplication
refactor dialogs, combined help, error, warning dialogs to info dialog
add InfoDialog.java
undo changes
fixed tools menu on api < 11
fixed tests
Merge pull request #68 from Catrobat/dialog_refactor

Dialog refactor
Implementation: @galstc05
Acceptance: @michaelmuenzer