Thumbnail image for mixture item in category detail. Closes #9.

* Add custom CSS for category pages.
* Add thumbnail for mixture item in category detail.
Add translation support for models. Closes #8.

* Add migrations for new language fields.
* Fix column names for translations.
* Add TransMeta metaclass into needed models.
* Add django-transmeta requirement as base.
* Fix to use the correct column on autofill for slug.
* Add migrations for translated slug fields.
* Change initial to store translated fields.
* Add auto fil for slug fields.
* Add slug to translate list.
* Change to filter slug by all translated fields.
* Change to use slug field instead of slugify name.
Merge branch 'issue#8-Use_TransMeta' into develop

Conflicts:
	poppurri/templates/category_detail.html
Merge branch 'develop'