Add travis.yml

Change CSS font strategy + better fallback

fix #487

Fix @cartes.data.gouv.fr/#25

* Only keep useful woff/woff2 fonts: http://davidensinger.com/2014/10/update-your-font-face-file-formats-to-just-use-woff-and-woff2/
* Fallback to system fonts: https://www.smashingmagazine.com/2015/11/using-system-ui-fonts-practical-guide/
* Declare fonts with correct weight/style to avoid the change to all elements: http://stackoverflow.com/a/21614532
* Switch from Bold to SemiBold to be consistent with the use of Light by default

Deal with ordered list as unordered ones in CSS

Remove useless leaflet tags from templates

Switch to Flexbox for main navigation

Not yet faster but it’s coming!

fix feedback anchor link to wiki (httpS)

Swap this wiki link to httpS
The wiki is now on httpS and sadly the httpS redirect causes #anchor links to be lost

cf https://github.com/omab/python-social-auth/blob/master/MIGRATING_TO_SOCIAL.md

We now have a data migration to add one default for each