PROD-117 - Modify cms-sdk to support product matching

This pull request makes slight modifications to support product matching.  It adds a method to check if the service is alive (we use this in our CMS healthcheck in Mumford).  It also updates some tests that are slow to pass because of timeouts (my team had to build this sdk close to 20 times before we got it to successfully complete its tests).  I also changed one test to check for a 401, not a 403, since I never received a 403 from 

NOTE: The api key and secret key are not valid for https://sandbox.cms.bazaarvoice.com and so these tests won't pass.  I don't know what the credentials would be, but the code works with the Mumford secret key.
We don't need to sign the request for alive check. Please remove this line.