column "is_superuser" is of type integer but expression is of type boolean DJANGO Error
It seems to me that you are using raw SQL queries instead of Django ORM calls and this causes portability issues when you switch database engines. I'd strongly suggest to use ORM if it's possible in your case. If not, then I'd say that you need to detect database engine on your own and construct queries depending on current engine.
In this case you could try to use 0 instead of false, I guess this should work both on SQLite and Postgres.
I could use some help.  My python 3.4 Django 1.7.4 site worked fine using sqlite.  Now I've moved it to Heroku which uses Postgres.  And when I try to create a user / password i get this error:

column "is_superuser" is of type integer but expression is of type boolean
LINE 1: ...15-02-08 19:23:26.965870+00:00', "is_superuser" = false, "us...
                                                             ^
HINT:  You will need to rewrite or cast the expression.

The last function call in the stack trace is:
/app/.heroku/python/lib/python3.4/site-packages/django/db/backends/utils.py in execute
                return self.cursor.execute(sql, params) ...
▶ Local vars

I don't have access to the base django code,  just the code on my app.  So any help getting this to work would be really helpful.