strands_datacentre

This new  package contains a single node that starts a MongoDB server, which can be used to store anything. I imagine using it to store both configuration data (eg. maps with meta-data ( patrolling waypoints), charging station parameters, diagnostics "on-call" contacts) and general long-term experiences (ros messages, particularly QSR rerpresentations of perception).

This package requires MongoDB and python-pmongo:
```
sudo apt-get install mongodb
sudo apt-get install python-pymongo
```

C++ and Python mongo wrappers are available, so I imagine client programs will often communicate directly with MongoDB directly rather than through ros service calls. However, for system parameters I suggest we create another node that loads parameters from the mongodb onto the ros parameter server, overlayed on top of a set of standard parameters allowing each partner to have there own config.