If the point of sanitization is to get rid of all non-alphanumeric
characters then Unicode characters should probably be forbidden too.
We can re-use the same sanitization function as used for cert 'name'
The plugin now supports loading details from local files rather than requiring them to be entered through the UI. This is especially relaent when Lemur is deployed on Kubernetes as the certificate, token, and current namespace will be injected into the pod. The location these details are injected are the defaults if no configuration details are supplied.
The plugin now supports deploying the secret in three different formats:
* Full - matches the formate used by the plugin prior to these changes.
* TLS - creates a secret of type kubernetes.io/tls and includes the certificate chain and private key, this format is used by many kubernetes features.
* Certificate - creates a secret containing only the certificate chain, suitable for use as trust authority where private keys should _NOT_ be deployed.
The deployed secret can now have a name set through the configuration options; the setting allows the insertion of the placeholder '{common_name}' which will be replaced by the certificate's common name value.
Debug level logging has been added.
The Kubernetes plugin was broken. There were two major issues:
* The server certificate was entered in a string input making it impossible (as far as I know) to enter a valid PEM certificate.
* The base64 encoding calls were passing strings where bytes were expected.
The fix to the first issue depends on #2218 and a change in the options structure. I've also included some improved input validation and logging.
