UI: Use new style for wiki

Depends on !1953

See the commits for more details, the messages mostly speak for themselves.

# Highlights

## Wiki Page

Before:

![Screen_Shot_2015-12-02_at_17.48.45](/uploads/aa53f768b8760f2e15d765e06d5ff773/Screen_Shot_2015-12-02_at_17.48.45.png)

After:

![Screen_Shot_2015-12-02_at_17.48.16](/uploads/f8a376651aff9c8de82621578aaeb002/Screen_Shot_2015-12-02_at_17.48.16.png)

## Edit Wiki Page

Before:

![Screen_Shot_2015-12-02_at_17.48.59](/uploads/c9ffddaca3156046b99cba11bdb0ea4f/Screen_Shot_2015-12-02_at_17.48.59.png)

After:

![Screen_Shot_2015-12-02_at_17.48.26](/uploads/1aa62049f120c91436ed68fd7441c156/Screen_Shot_2015-12-02_at_17.48.26.png)

See merge request !1967