Additional logging in MailServiceTest.pollForMatchingMail

This will help figuring out what went wrong when the test fails with "No matching MimeProperties found in 45 seconds"
Don't check BCC at all

Since the BCC field should be removed by the destination server, we shouldn't use it to match received email messages with the expected email message. GMail used to strip the BCC, but now it apparently doesn't strip it if it's the same as the sender's address.
Upgrade endpoints generated version.
Move "site" and "dist" to new profile.
Upgrade to GAE 1.9.17a
Add GCloud support.
Make VM optional in appengine-web.xml.
Use new GCloud container.
Initial HttpSession tests.