GitLab

* Added denormalized data about semesters, majors and minors in university model
* added function to compute it
* Added function to cron
* new FilterHandler in the front to handle / cache the filtering
* Tweaked map and search components to display the right stuff
* Map now displays in a different color the elements that have been filtered

* Renamed spacilities field to majors
* Fixed bugged in downshift multiple (couldn't add same after delete)
* Deleted useless code in offer

Linked to #31

Pagination:
* Paginated endpoints for offers and previous exchanges,
* Added front component to display paginated data,
* Display offer in the front

Filter on previous exchanges:
* Added a denormalized model to store information
* Compute it in cron and in transaction
* Filter in front

Closes #123

* Setup cron to automatically update remote data
* Support partial (login based) utc data update
* Tweaked models to record untouched or unlincked situations
* take them into account in the front and the back,
* Auto creation of general feedback also
* Added info about unlinked utc partners in the front
* Added button to request update ent data
* Added university offer module to the front

Other:
* Tweaked loading scripts
* tweaked models
* Fixed SelectField

Closes #28