Create symlinks/files in /home/vagrant

* symlink /home/vagrant/devstack to /home/stack/devstack
* symlink /home/vagrant/grenade to /home/stack/grenade
* use stack's .bashrc for the vagrant uesr

Change-Id: I79dc58495c62b12c08783b38f64e4505bd4eec02
Merge "Create symlinks/files in /home/vagrant"