Several minor improvements to allow setting up the dev env from a VM with Vagrant

Vagrant is a utility to allow the creation of portable dev environments (www.vagrantup.com)

- '.vagrant' is added to .gitignore, as it's unique per machine
- Vagrantfile is the config file for the vagrant machine, with the forwarded ports.
- xcsoar is added as a git submodule to have the binary symlink already created inside the vm
- development.ini is changed from 127.0.0.1 to 0.0.0.0 to allow access from outside the vm
- setup.py is updated with a Pylons dependency = 1.0 to circunvent an error about a dependency installing Pylons 1.0.1
Specify SQLAlchemy version to 0.7.9, otherwise errors occur in the new user form