Start writing out openssl index file for CRL generation.
Write PEM CRL to temp dir with openssl.
Move PEM encoding logic to a separate utility.

This prevents a circular dependency between CrlFileUtil, which needs to do PEM
encoding, and the PKIUtility implementations, which previously did PEM
encoding, but now need to read a CRL file.

Switched bouncycastle implementation to just use the new PEM encoding logic
previously in the JSSPKIUtility. The code looks straightforward enough.
Fix issue with Openssl needing hex serials.