Add simple shell script for running manage.py commands

All arguments are passed through, so you can do:
`./manage.sh runserver`
or
`./manage.py migrate core`
or any other management command, from your host, without having to
wrap you call with envdir
Use sane defaults for the Django runserver

If you don't use 0.0.0.0:8000, the runserver is only accessible from
the VM itself.
Merge pull request #68 from maurizi/run-tools

Add simple shell script for running manage.py commands