Improve consistency of baseURL trailing slash handling.
Improve consistency of baseURL trailing slash handling.

There were mismatches between the documentation and actual behavior
of how the baseURL trailing slash was handled.

There were also inconsistency of the gerritURL/endpoint parameter name
in the documentation of NewClient and the actual function signature.

This change fixes those and simplifies code.

andygrunwald/diffy,andygrunwald/go-gerrit