Add option to remove signing cert entry          In the migration case, it is useful to delete the initially     created signing certificate database record and have that be     imported through the ldif data import instead.          Therefore, we add an option to remove this entry.  The user     also needs to provide the serial number for the entry.          This resolves the following tickets/BZs:     BZ# 1409949/Trac 2573 - CA Certificate Issuance Date displayed        on CA website incorrect     BZ# 1409946/Trac 2571 -  Request ID undefined for CA signing        certificate Please review, Ade