Set mongodb configuration for remote access

This pull request adds a file provisioner which copies a local mongodb.conf file to the guest. The shell provisioner then moves it into the right directory (/etc) and restarts the service to reload the configuration.

The contents of mongodb.conf allow remote access by binding the ip to 0.0.0.0 instead of the default 127.0.0.1,

The reason we have to go through the file provisioner and then move the file instead of uploading it directly into /etc is that file provisioners are not run as root but as the vagrant user, which means the provisioner does not have write access to /etc.