Add Mozilla Persona Omniauth Gem and initializer
Add (ui-only) Persona button to login modal
Add basic Persona functionality

1. No session integration yet, so automatic login/logout events are suppressed.

2. Popup blockers must be disabled: submits form to target="_blank"
Use AJAX for submitting Persona credentials.

Fixes issue with needing to unblock popups.
Make Persona configurable
add basic coding style guidelines to CONTRIBUTING.md
Fix display host for onebox
Fix weirdly indented code
Update nginx.sample.conf
updated Gemfile.lock to take into account the rb-inotify's version bump
Position the selected post more reliably below the header
better french traduction...

... regarding the minimum entropies
Merge pull request #341 from ZogStriP/patch-1

better french traduction...
Merge pull request #338 from ZogStriP/updated-gemfile-lock

updated Gemfile.lock to take into account the rb-inotify's version bump
implement translations into static pages (FAQ, TOS) + an example of CZ translation
Don't double-up on #main-outlet when static content is rendered through Ember
update vagrant documentation

to deal with eventual troubles while downloading the box
added the gear icon to the "Admin" button on the user page
update both the title & the category when editing the first post

using the "edit this post" action beneath the post.
some more extracted strings for translation