django added firebird support

[ED:django is like RoR implemented in python]
Just attached the firebird backend and a patch file. Firebird has a problem, names can’t bigger than 31 chars for tables, fields, constraints, etc. In auth app needed to change user_premissions to permissions so the many to many table name doens’t get too big… must be a way we can workaround this…

Another thing, i just got a testing project working installing the apps one by one, with syncdb, somehow, not all the generators/sequences are being created.

It passed the majority of tests, again one by one as i needed to change the tables names in Meta class for some models. A relevant test failure was in lookups tests with ‘startswith’.

This should not be used for production, please test.