validate from backend (bug 1129713)

In certain cases we were depending on CMS to validate PKI tokens
but that is not necessary, and by passes the revocation check

Change-Id: I9d7e60b074aa8c8859971618fed20c8cde2220c4
(cherry picked from commit 255b1d43500f5d98ec73a0056525b492b14fec05)