Trading Client Backend - Rev 1

This PR notably adds the Trading service and OrderBook model, used to buy/sell currency.

In addition, there is a temporary "trade" page that will be removed prior to merging with master that is a testbed for functionality.  
It looks like the merge dropped the ```authenticate: true``` from trading.

Should we leave ```/trade``` as a reference, then remove it once ```/trading``` is done or use the ```/trade``` URL instead of ```/trading```?