Add Vendor Category to Nuxeo Marketplace

Requirements

In order to allow partners to share publicly their own marketplace package, we need to create a new "Vendor" category. This category is located at the same hierarchy level as "Packages by type" or "Packages by category".

The children entries corresponds to each packages created by a specific partner (Amexio, Sollan, Teknei, Infosquare etc.). These entries should be stored in a vocabulary and managed by ourselves. 

Expected behaviour

• User go to marketplace.nuxeo.com without being logged
• In the "Browse by filters" section, a category called "Packages by vendor" is present, with some subentries.
• If a user clicks on a subentry (corresponding to a partner), the filter is applied and it lists only packages with the corresponding vendor.
• The user can't download the package until he is logged in.
• In a package details screen, clicking on the vendor name should take you to the list of packages from this specific vendor

Side notes

• Currently, the vendor field is a freetext. It should be updated to be a vocabulary.
• Ideally, we would need to be autonomous to manage the vocabulary (at least Gregory Carlin as a start). 
• The URL is specific by partner