[dynamicCharts] display x axis on histograms
[dynamicCharts] create filters
[dynamicCharts] include nouislider
[dynamicCharts] add age filter
[dynamicCharts] add libs to karma.conf.js
[dynamicCharts] link filters to API
[dynamicCharts] pass IDs and not data to the directive
[dynamicCharts] update embeddable version
Merged develop into feature/dynamiccharts
Added position field to ThematicSerializer
Updated front-end specs for UserPosition and its positions wrapper
Renamed utilsSpecs in servicesSpecs
Refactored (and made stronger) navigation system
Tested all answer typologies in API
Added missing use case test: gender question answering
Started implementation of answer creation on question directives
Changed the way we validate RadioAnswer (RadioSerializer)
Cleaned (a bit) API views + added separated view for user position
Incremented number of add_booleananswer migration (check commit body)
This migration was in conflict with the previous (0026) migration which added
slug field to thematic model.

If you have any trouble with these last migrations please let me now (github.com/pbellon)
Refactored and strenghtened API & core relations