Though a CA would accept two year validity, we were getting error for being beyond 2 years.
This is because our current conversion is just current date plus 2 years,
1/25/2019 + 2 years ==> 1/25/2019
This is more strictly seen two years and 1 day extra, violating the 2 year's limit.
This is done in two places:
* Certificate import validator -- throws validation errors.
* Certificate model constructor -- to ensure integrity of Lemur's data
even when issuer plugins or other code paths have bugs.
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.
