Resolve "L'ajout d'un article déjà existant en crée un nouveau"

Closes #38

See merge request !28

Slightly changing the signature for Article.add_new_url and overloading the create method for the Serializers

Resolve "Preprocess and import v1 data"

Closes #21

See merge request !25

Merge branch '21-preprocess-and-import-v1-data' of git.laquadrature.net:la-quadrature-du-net/rpteam/rp into 21-preprocess-and-import-v1-data

Resolve "Get a status code for original text"

Closes #32

See merge request !27

Resolve "Backend : parsing contenu/métadonnées/images"

See merge request !26

Resolve "Backend : parsing contenu/métadonnées/images"

See merge request !21

Adding the missing method to serialize

See merge request !20

Adding documentation for undocumented fields

See merge request !18

Merge branch '31-interface-admin-permettre-la-creation-de-contenu-directement-depuis-l-nterface-admin' into 'rp2'

Resolve "Interface admin: Permettre la création de contenu directement depuis l'nterface admin"

Closes #31

See merge request !17

Resolve "API REST : push/pull contenu"

See merge request !16

Let's sync db on migrate, in case some apps (such as django_und_vote) don't have migrations, but needs tables to be created