Implement sanity checks and improve metrics

[anita-tenjarla]

• Improved CA cert comparison -- no longer byte comparison
• Implemented sanity check that runs in manager server: checks that keysize and algorithm on disk match spec, hostnames on disk match spec, and cert+key on disk are valid keypair
• Improved prometheus metrics: added labels to specify spec/cert in question. New metrics include: AlgorithmMismatchCount, KeysizeMismatchCount, HostnameMismatchCount, KeypairMismatchCount, ManagerInterval, ActionCount.