When not found return None and do not try to run len() on None

Return an instance and not a list of len 1 anymore

In construct and check data

with make deb . Next commit will update the README

Now backref seems to work at creation of a Person linked with a text the Person UID is appended to Text.linked_persons

Triggered a bug in wrong Integer DH tests

Return the value of this datahandler when empty

refs #131

The dedup mechanism was using a cast of list to set. But sometimes, filters contains list, and list are not hashable...

refs #131

Methods are written.
They are not called by anyone and the only tests that were done is that no syntax error is raised.
( refs #131 )

- deletion of unused attributes
- copy the back_reference checks in _set_back_reference function and use it in Reference.__init__()

Now when running distclean ALL files generated by the ./bootstrap && ./configure && make are deleted.
Maybe it's not a good idea because it's not the purpose of distclean target...

Using $pkgpythondir instead of $pythondir in Makefile.am
Solves a bug that put installed files in site-packages instead of dist-packages on debian

IMPORTANT : tests are broken. See details below

A new lodel/buildconf.py.ini file created. It will be transformed to a lodel/buildconf.py file by ./configure .
This file goal is to store build time constant (for the moment the presence of pymongo).
You have to build lodel2 before being able to run the tests.

Created groups (they can be found under the "Modules" menu -_- )
Created new pages : on LeAPI EditorialModel Plugins etc