add support to insert inline image

Refactor StyleNameGenerator into ObjectNameGenerator 
- moved getAllStyleNames from Formatting to ObjectNameGenerator 
- renamed StyleNameGeneratorTest to ObjectNameGeneratorTest and added a couple of more unit tests 
Add support for inserting inline images into text document 
- implement OpAddBlob, OpRemoveBlob and OpInsertImage 
Add insert image button to the editor

moved from https://gitorious.org/webodf/webodf/merge_requests/163