Google Cloud Auth and debugging tools

• Correct bug of incorrect redirect URL when no port (#45)
• Catch error for retry if no status response at all
• Fix bug where unnamed customConfigs were ignored
• Fixes to discovery API package creations, order of parameters and NULL parameters
• Add authentication option when using Google Compute Engine gar_gce_auth() (#52)
• Add a warning if the cached .httr-oauth token has different scopes to the ones specified at time of authentication (#53)
• Add debug body aid: if option(googleAuthR.verbose = 0) then a request with a body will write to a file request_debug.rds in working directory
• Passing in a file location token to gar_auth("file-location.rds") will only load the first element [[1]] if that token is a list of Token2.0 class objects
• Add debug tool gar_token_info() which will report on current authentication. Available at options(googleAuthR.verbose = 2)