'+' in wikipedia links

When a user want to reference a wikipedia page which contains a '+'
char, he could not use the wikipedia dedicated syntax.

This commit modifies the regular expression to allow one such a use.

This fixes
http://linuxfr.org/suivi/les-liens-wikip%C3%A9dia-ne-g%C3%A8rent-pas-les
Display links to wikipedia without prefix

When a user wants to reference a wikipedia page, in another language
than french, or reference the wiktionary, he could use a prefix like 'en' or 'wikt'.
This works well, but the prefix is displayed in the result page.

This commit try to parse the given input, to check if there is prefix,
and in this case do not display the prefix.

This fixes
http://linuxfr.org/suivi/option-de-langue-pour-les-liens-wikipedia
A bit of refactoring on wikilinks
Update gems
Add a teletype button to markitup
Use Redcarpet 2 for markdown rendering
Wording
Improve content and users stats
Fix stats
Revert the change on comments state (the query is way too slow)
Fix link encoding
CSS
CSS
Update Rails
Update the EventSource polyfill lib
Add validation on CSS
Fix URL redirection in the redaction space
Add format validation on logins
Remove hacks for Ruby 1.8
Don't validate login on update