v0.4.1

Manager resource and null (zero) values (#19)

* Manager resource and null (zero) values

Hirefire API changed how it handles null values in the manager resource,
specifically:
- notify*
- *scale_timeout
- *scale_limit

Also, logdrain in the application resource now requires a specific format.
Plus, updated readme to explain how to run terrafrom with a local build.

* Run terraform with a dev version of the provider