Incorrect/Misleading key name in landscape-client charm and landscape-config tool, "ssl public key"

[Yamen Hatahet]

The issue is in the landscape-client charm's config, with the key name "ssl-public-key", as well as in the landscape-config tool (which is part of the landscape-client), with the cli option -k SS:_PUBLIC KEY, --ssl-public-key=SSL_PUBLIC_KEY.

Below is the entry in the landscape-client charmhub page:

```
ssl-public-key | string

The CA certificate to verify the server certificate with. This can be
a path to a file, or a base64 encoded entry of the certificate itself,
prefixed with "base64:". This config is only used if the message server
URL given above starts with https.
```

And in the man page of landscape-config:

```
       -k SSL_PUBLIC_KEY, --ssl-public-key=SSL_PUBLIC_KEY
              The SSL CA certificate to verify the server with. Only used if the server URL to which we connect is https.
```
Additionally, when using the `landscape-config` tool, it will ask the user to supply the --ssl-public-key option, so the change needs to be done on all occurrences.

The word "key" should be changed to something more accurate, such as "cert".

[Bartosz Woronicz (mastier1)]

For the sake of consistency with other charms like for openstack charms I would go with ssl-ca

Also the landscape client should be update to match the correct naming convention

```
root@vault-1:~# cat /etc/landscape/client.conf|grep ssl_public_key
ssl_public_key = /etc/ssl/certs/landscape_server_ca.crt
root@vault-1:~# head /etc/ssl/certs/landscape_server_ca.crt
-----BEGIN CERTIFICATE-----
MIIEOTCCAyGg.................J4Z4wDQYJKoZIhvcNAQEL
BQAwLDEq....................1VEIEVudGVycHJpc2UgSXNzdWluZyBDQSAx
```

[Bartosz Woronicz (mastier1)]

Also the need for base64: prefix is redundant.
It should be served on the charm level to check whether the input is base64, all other charms are doing it this way
https://github.com/juju/charm-helpers/blob/master/charmhelpers/contrib/openstack/cert_utils.py#L344

For the elegance you may add some the cert validation itself

[Yamen Hatahet (yhatahet)]

Completely Agree with @mastier1 . The base64 prefix is an easy way to make errors, and sometimes hard to debug.