* Rename crlConfig to CrlConfig.
Rename defaultCrlConfig to DefaultCrlConfig.
* Move CrlConfig and DefaultCrlConfig to new package pki/revocation.
* Rename revocationInfo to RevocationInfo.
* Move RevocationInfo to pki/revocation.
* Add StorageContext interface to PKI's revocation package.
* Add CrlBuilderType interface to pki_backend package.
The purpose of the interface is to make it possible to gradually move (refactor)
CrlBuilder to the revocation package.
* Move CrlConfig and DefaultCrlConfig to package pki_backend.
* Make StorageContext.CrlBuilder() return a CrlBuilderType.
Add methods SetLastDeltaRebuildCheckTime() and ShouldInvalidate() to
CrlBuilderType.
* Move fetchIssuerMapForRevocationChecking to PKI's revocation package.
* Run make fmt.
