[FACTO] listes (map, stop) + scores (occurrences, specificity) + ngrams tools to insert ngrams fastly. Need to be tested after NodeHyperdata table creation.

journals view, with new API route for journal facet, dynatable css factorized (applies for all corpora templates) and menu.html providing a corpora navbar to switch between journals and documents

[FEAT] linked nodes with links (cf. `gargantext.constants` and `gargantext.models.Node.as_list()`
[FEAT] implemented an `ngrams` pseudo-attribute on `gargantext.models.Node` (available from REST api)
[FEAT] on REST API, renamed GET parameter `type[]` to `types[]`
[FEAT] `json_dumps()` can even serialize SQLAlchemy models and models now

(couldn't get it to work with 3.5)

[FEAT] serializing of JSON is much better and has its own module
[CODE] upgraded to Python 3.5 (`traceback.TracebackException`)
[CODE] did some cleaning, here and there...