FigureServiceTest: new test stub

Test is now based on scalatest instead of spec2
Figures: add support for figures to existing classes

Assets now generate figures and attach them to abstracts
AbstractService handles figures on delete
FigureService: implement all methods (untested)
gitignore: exclude figures from git
Assets: fix small bug in assets generation for figures
FigureService: fix some bugs
FigureServiceTest: all test implemented and running