Multiple objects won't have proper endpoint

[dblessing]

If a user instantiates multiple client objects the base_uri won't be set correctly because it's a class method. See https://github.com/dblessing/rundeck-ruby/blob/master/lib/rundeck/request.rb#L58

HTTParty doesn't support setting this another way. We will have to manage the endpoint differently, maybe as part of the get, post, etc methods.