[fix] google engine (close #193)

Moar engines

[enh] improve response time. close #100

General cookies

Add '?' bang to the autocompleter

Russian translation

Two colors are needed so I use a space in the cookie and a split in jinja to "encode" and "decode" them.
We should enforce that each theme if they must use a cookie, prefix its name with the name of the theme.

The color proposed here are based on bootstrap. We could use others.

improve oscar-template

[enh] image-proxy : handle ETag and date related headers, add hash to URL

Thumbnails

Copy all the folders of 'static'

- Modify engines to create/fetch an URL for the thumbnails
- Modify themes to show thumbnails instead of full images.

In Courgette, the result is not very beautiful. Should we change it ?