move django-extensions to main requirements.
remove the search field for normal users, it's just too slow to be usable.
Merge branch 'develop' into feature/interface-reldb

Conflicts:
	config/requirements.txt
preferences on reldb (WIP).
port preferences to reldb.
read model update (attr factorization).
item.a_feed update.
article.name.
views updates for realdb (WIP).
templates updates for reldb (WIP).
coretags update for reldb.