enabled admin; added donor update pg; modd Donor model

Added donor_update view and template for updating a donor's unfo.
Each donor has a url with a 512 bit random b64 string.

Donor model creates secret key for url on save.

Also created donor model form. enabled Donor model in admin.
Merge branch 'master' of github.com:DCPython/dcpython-django
added .gitignore
Merge pull request #4 from edwelker/master

added .gitignore