Fix wrong handling moveTo parameter on role destroy.
Fix wrong handling role points update.

Additionally it moves the logic from serializer to resource.
Add temporal fix to history attachments changes rendering.
Move some userstories test to right location.
Rename project tests.
Merge pull request #123 from taigaio/random-fixes

A collection minor fixes + hotfixes
Fix incorrect handling of userstory rolepoints update process.

The current implementation allows duplicate points values in one project,
and because of it, unexpected MultipleObjectsReturned can be raised with
previous update_role_points code. The new one fixes this.

Additionally, in some circumstances, the project does not have any points
with None as value, that causes also unexpected errors. The new
implementation fixes it creating a points instance with None as value
if it not exists.