Finish moving all full URL setting to `setRawUrlPath` and change `withUrlPath` to not require starting `/`

[bitwiseman]

#697 (comment)

This will require looking at each call to withUrlPath to determine if it is passing a tail URL (starting with "/") or passing a full url (starting with http).

Oh, look here's one:
https://github.com/github-api/github-api/blob/ff3136df7069d22d937daa8f2cddc357c777e07e/src/main/java/org/kohsuke/github/GHBranch.java#L104

There more in that class as well, but there are no tests for a number of those methods.

So, each case of this needs a test written to show it works and then change to use setRawUrlPath. Finally, when we should block withUrlPath from accepting full urls.