MINOR: ssl/cli: rework 'set ssl cert' as 'set/commit'

MINOR: ssl/cli: rework 'set ssl cert' as 'set/commit'

This patch splits the 'set ssl cert' CLI command into 2 commands.

The previous way of updating the certificate on the CLI was limited with
the bundles. It was only able to apply one of the tree part of the
certificate during an update, which mean that we needed 3 updates to
update a full 3 certs bundle.

It was also not possible to apply atomically several part of a
certificate with the ability to rollback on error. (For example applying
a .pem, then a .ocsp, then a .sctl)

The command 'set ssl cert' will now duplicate the certificate (or
bundle) and update it in a temporary transaction..

The second command 'commit ssl cert' will commit all the changes made
during the transaction for the certificate.

This commit breaks the ability to update a certificate which was used as
a unique file and as a bundle in the HAProxy configuration. This way of
using the certificates wasn't making any sense.

Example:

	// For a bundle:

	$ echo -e "set ssl cert localhost.pem.rsa <<\n$(cat kikyo.pem.rsa)\n" | socat /tmp/sock1 -
	Transaction created for certificate localhost.pem!

	$ echo -e "set ssl cert localhost.pem.dsa <<\n$(cat kikyo.pem.dsa)\n" | socat /tmp/sock1 -
	Transaction updated for certificate localhost.pem!

	$ echo -e "set ssl cert localhost.pem.ecdsa <<\n$(cat kikyo.pem.ecdsa)\n" | socat /tmp/sock1 -
	Transaction updated for certificate localhost.pem!

	$ echo "commit ssl cert localhost.pem" | socat /tmp/sock1 -
	Committing localhost.pem.
	Success!