1026501: Preserve PKI directories and have rpm own them.

Merged duplicated cert directory cleanup code into one method.

/etc/pki/consumer and /etc/pki/entitlement will now be preserved when you
unregister or clean.

We now remove just the identity cert and key as their filenames are known.

For entitlement directory we remove any files ending with .pem.

subscription-manager rpm will now create and own these directories on
installation.

File monitoring code needs no modifications as we check mtime, which adjusts on
any file addition/removal within the directories.
Fix test failure if run on system that is registered.
Make sure entitlement cert directory exists before we clean it out.
Use glob for finding entitlement certs to remove.
Merge pull request #894 from candlepin/dgoodwin/certdirs

1026501: Preserve PKI directories and have rpm own them.