Replaces map(lambda k: …) with way faster list comprehensions.

According to timeit, it's 4 times faster for small lists (3 items)
and 20 % faster for huge lists (15000 items).
Tiny optimizations.
dict.iteritems > dict.items for Python 3.
Avoids a mutable object in a function parameter.
Removes an unused util.
Converts unpickle to a static method.
Moves a statement outside of a try…except block.
Fixes a potential bug.
Adds FIXMEs and removes unused imports in stats/views.py.
Merge pull request #46 from BertrandBordage/master

Small optimization & cleanups + fixes a potential bug.
Add django >= 1.6 timeout=None compatibility.
Update CHANGES.rst
Update documentation.
Remove duplicated content from README.rst.
Propagate django1.6 behavior to rest sub clients.
Change them to default sphinx theme.
Documentation reorganization.
Set old test runner on settings.
Set django 1.6 for .travis.yml
Fix wrong node resolve method on hashring module. (fix #48)