We should mention GOOGLE_APPLICATION_CREDENTIALS in the Authentication section. #331
Description
The main gcloud-java README.md contains an authentication section however this section does not
mention the option of using the GOOGLE_APPLICATION_CREDENTIALS environment variable to point to a key file.
@mziccard I now wonder if we need the GCLOUD_TESTS_KEY and GCLOUD_TESTS_PROJECT_ID in the RemoteGcsHelper as GOOGLE_APPLICATION_CREDENTIALS could be used instead of the former and GCLOUD_PROJECT could be used instead of the latter.