[fix] Adding DjangoExtensions (useful dev tools) to INSTALLED_APPS
[add] Display time with naturaltime filter
Merge branch 'master' of https://github.com/C4ptainCrunch/beta402
[add] OneParentNode.move() to move a OneParentNode from a parent to another
[enh] Add some variables to Makefile.

Now use `make`
Then `make stop`
[fix] Also ignore helper files created by Makefile
Merge branch 'master' of https://github.com/C4ptainCrunch/beta402
[fix] Adapting README to new Makefile
[fix] Solving some double inheritance issues
[enh] Makefile more verbose
Merge branch 'master' of git://github.com/titouanc/beta402

Conflicts:
	polydag/models.py
[fix/enh] A doc now may not have multiple parents. So a parent id may be used for the viewer (done).
Files are now stored in a directory  whitch name id the parent id