attempt at an auto retry for the last build

Regarding issue #1 so you can get a better grasp on what I'm trying to do.
@Linuturk - I see what the issue is now.  When `build_num` is last, the code to get the actual build number (lines 114-121) is right.  The problem is the existing code is called before we set `build_num`.  The reason for this is the call on line 117 is async, so we immediately jump to line 122 before the response from the CircleCI API comes in.

The fix is to wait to call the retry api until after the response comes in.

Let me know if that doesn't make sense.