Add logging to gemfile to fix specs

[dazuma]

It looks like the logging gem used to be in the bundle implicitly due to a transitive dependency, but has been removed. This is why the tests have been breaking. Adding it explicitly because the spec helper requires it.

[coveralls]

Coverage increased (+0.07%) to 96.064% when pulling b33c970 on dazuma:logging-fix into 24be95a on google:master.

[dazuma]

Also made two more changes:

• Removed two enormous puts calls that were overwhelming the travis logs and making test output useless.
• Added the new Signet::RemoteServerError (see Handle 5xx errors with RemoteServerError signet#100) to the list of retriable auth errors, to make HttpCommand tests pass.