Simplifying auth for tests.

Added helper method and calling it to get the authentication setup for
the test suite. This way you can use the cert directly from the xplat
"account cert export" command without having to go through a bunch more
hoops.
Fixed scmservice, service bus management tests
Updated sql management test
Fixed sqlservice tests
Updated website management service tests
Update to storage management client tests
Merge pull request #1201 from christav/test-auth-fixes

Simplifying auth for tests.