added permission methods to conf service
test for permissions for conference service
permissions management done on the service layer with tests
controllers and one test for managing permissions done
permissions on controller level done
Merge remote-tracking branch 'upstream/master'
Merge pull request #88 from asobolev/master

permissions management for Conference / Abstract (service, controller)

LGTM
Abstract: add cascade fixes issue with updates
model.js: toObject converts "" to null
editor.js: cancel editing in modal boxes
editor.js: refactoring method names
editor.js: display character limits in text editor
Abstract: add isTalk and reasonForTalk
Model: new model for topic

Move model AbstractGroup to own file
Model: better equal method
Topic: add toString method
Conference: add topic to conference model
Topic: support topics in assets, services and js models
Bootstrap: add glyphicons
editor.js: improved editor