DEV-50173 - investigate certificate code performance

DEV-50166 - LLBasicCertificateChain::validate calls in log
Added caching of certificates that have been validated.
The sha1 hash for the certificate is stored and is associated
with the from and to times.  When the certificate is validated,
the code determines whether the certificate has successfully
been validated before by looking for it in the cache, and then
checks the date of the cert.  If that is successful,
the validation calls with success.

Otherwise, it proceeds to do a full validation of the certificate.