BUG/MINOR: ssl/cli: certs added from the CLI can't be deleted

BUG/MINOR: ssl/cli: certs added from the CLI can't be deleted

In ticket #706 it was reported that a certificate which was added from
the CLI can't be removed with 'del ssl cert' and is marked as 'Used'.

The problem is that the certificate instances are not added to the
created crtlist_entry, so they can't be deleted upon a 'del ssl
crt-list', and the store can't never be marked 'Unused' because of this.

This patch fixes the issue by adding the instances to the crtlist_entry,
which is enough to fix the issue.