Previously, we used to create one Google OAuth callback url entry
per subdomain. This commit allows us to authenticate subdomain users
against a single Google OAuth callback url entry.
For some reason, we use 'load' function but it doesn't exist in the JWT
library code. This commit updates the code to use the correct interface
of the JWT library.
The signature verification is done by the decode function.
Umair Khan
Tim Abbott
hackerkid