rules: add function to get elasticsearch health
suricata: add info page

It is used to return information that will be used by main
component to display status of different composant. For now
only a function checking if suricata is running is implemented.
rules: display suricata and ES status

This patch adds a new panel in the left sidebar to display the
status of Suricata and Elasticsearch. For Suricata we are using
the function provided by the middleware. For Elasticsearch we are
querying the cluster status.
suricata: add info on disk
rules: display disk status
rules: ES sttatus display is conditional