added simple Vagrantfile with whole development stack

Hi,

I added a Vagrantfile that creates a virtual machine with the whole development stack.

Software needed:
- virtualbox (http://virtualbox.org)
- vagrant (http://vagrantup.com)

Essential commands:

```
# create (or start) vm
vagrant up

# stop the vm
vagrant halt

# delete the vm
vagrant destroy

# ssh into the vm
vagrant ssh
```

After the vm setup the following commands must be run within the vm:
```
# change to root directory of the project (/ of the git repository)
cd /vagrant

# load modules
npm install

# optional: run tests
npm test

# run the application
npm start
```

The ports for the application and mongodb are forwarded from the host to the guest. e.g. it is possible to access the application via http://localhost:17124 on the host and the mongo instance using "mongo" on the host (if available)