Provide Users an Easier Way to Change Certificates

[Zalgo2462]

The installer currently generates self signed certificates to encrypt communications to the Elastic server. We could replace the self signed certificates by having users add volume mounts to replace the installed certificates in the elasticsearch and kibana containers. We should wrap this mechanism and make it more user friendly.

[Zalgo2462]

Today, we are volume mounting in the certificates, but no one has tried replacing them. We just need to verify and document that users can change out the certificates in /etc/BeaKer/certificates, reload beaker with a beaker down and beaker up -d, and have it all work.