add some new methods for our interface
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django-model & webhooks

Adds a new Django model, that maps CloseIO to Django fields.
It includes a separate manager and pseudo decorators for field mapping
as well as mapping functions.
The webhook dispatches several signals that one can connect to.

UnitTests for Django model wrapper and webhooks

tests
 - model loading from closeIO
 - model saving
 - model loading form db
 - field mapping
 - custom field mapping
 - value conversion between db and closeIO
 - lazy loading of closeio values for existing objects
 - webhooks and signals