[model] Abstract: add 'sortId' field
[services] Abstract: Order by sortId, title
[js/model] add sortId member to Abstract class
[views+css] AbstractList: add sortId to the list view
[views] AbstractList: fix the sammy group route
[views+js] Enable group filtering and highlight active tab
Merge pull request #65 from gicmo/sortId

Implement Abstract.sortId and enable client side filtering based on it

OK
Affiliation: add a position attribute to the model
Author: add a position field to the model

Add a transient field affiliationPositions to the model,
 that can be used by the service class to define the n-to-m
 relationship between authors and affiliations.
serializer: adopt to model changes

AuthorFormat: reads and writes position and affiliations
AffiliationFormat: reads and writes  position
Assets: adopt test data to model changes model

Test data changed for Author and Affiliation
serializer: fix small bug in AuthorFormat.writes
serializer: adopt test
TestAll: add ConferenceCtrlTest