Add add_run command, btw something unserializable in TestRun so that's
why i created this slimmed-down create-only MasterTestRun
rename this class
Add command close_run to retailmenot branch
Clean up some schoolboy errors with comments and naming
Add functionality to allow the new addTestRun api call to actually 
return the newly created TestRun as per the testrails api suggests.
Also add the getTestRun call
Merge pull request #2 from colinmccormack/addRunBranch

Add run branch. We'll want to add unit tests and potentially genericize the postRESTBodyReturn method, but I wanted to get this in quickly. Thanks Colin!