Fixes bug 1254 and bug 1247

Update the ingress rules to be explicit about version to avoid
extensions/v1beta1 Ingress is deprecated in v1.14+ message.
Use kubectl annotate instead of kubectl replace.
Ensure microk8s is in ready state before installing juju.
Report error if non-existing vca is requested.
Expose prometheus and grafana.

Change-Id: I0a8aa78c5c9be3163918c0b08b38b4c47d8fae6c
Signed-off-by: beierlm <mark.beierl@canonical.com>