add license in the README introduction
setup documentation
Added features proposal
Fixed nested list.
Added database model suggestion.
Add main usages and security notes
Added idea about configuring accounts using python dict
First draft of version 0.1
Added example usages of receivers, senders and processors
Added info for contributors
Moved test packages from requirements to setup.py
Removed requirements.txt from travis.
Merge github.com:django-poste-restante/django-poste-restante
integrated proposal document to the Sphinx documentation