Fixes broken links when using URLs like http://host/kibana

Fixes bad links when using a reverse proxy and a sub-directory like this Apache config:

ProxyPreserveHost On
ProxyPass /kibana/ http://localhost:5601/
ProxyPassReverse /kibana/ http://localhost:5601/

Links to events are currently pointing to the root (/#eventid) and not to the sub-directory (/kibana/#eventid).