Allow rbt api-get to be used outside of a checkout.

Review Request #7812 — Created Dec. 17, 2015 and submitted — Latest diff uploaded

Information

RBTools
release-0.7.x

Reviewers

rbt api-get required a checkout in order to locate the server to connect
to. However, the checkout wasn't needed for anything else, and limited
the usefulness.

Now, if --server is passed, a local checkout isn't needed at all. It
will simply perform the request at the server provided.

Tested outside of a checkout, specifying --server=http://localhost:8080.

Tested inside a repository, without --server.