Add rights fields for flashmob model

* Editing rights
* Invitation rights
* Documents adding rights
Add model for comments
бла бла бла
Make membership_type enum

Also validate enum fields before putting into database
Fix jshint warnings
Merge branch 'firstVersionFlashmobs'
Merge branch 'master' into design

Conflicts:
	views/registration.ejs
Apply layout and registration form from new design