Updating README section of how to run rb-gateway server
Added 2 functions:
1) (webhook *Webhook)Delete
2) (webhook *Webhook)Disable
Adding testing for webhook.go. Need to figure out how to read the http responses from my dummy URL.
I read an article disgusting doing the teardown and setup in main_test.go and having individual functions there instead of in their own test file. I need to look at it some more to decide where to put this "setup/teardown" logic.
Also it looks like this review amalgamated all my changes along with a previous student's work that I used as a patch. Here are their changes that I applied (and modified a little): https://reviews.reviewboard.org/r/9402/
