Adds a fixture and preloads db

Adding a fixture that preloads the db each time the app starts. Useful
when continually fubar'ing the db state. Once it becomes a little more
stable, we'll pull it out.
Remove meta field from trades list

Angular works OOTB with an array of objects and doesn't like this extra
layer of complexity.
Changes schema for trade model

Probability of profit should be a number
Hooking up angular resource to backend