Various changes; see below

- More stuff to git ignore
- Set VM memory down to 1024
- Added line to provisioner to add dehr user to vagrant group
- Installer now creates /tmp/dehr and assigns it to dehr user+group
- Installer now configures uwsgi vassal to allow g+rw access to socket
- get_install_dir() now produces an error for missing --install
- Same for get_var_dir