Fix front health checking

- Specified seperated /health path in order to allow for healthcheck even if webmail and admin are not seletectd. This also allows healthchecking fom external services like DNS load balancers;
- Make curl not to fail on TLS because localhost is not included in the certificates.

core/nginx/Dockerfile

@@ -13,4 +13,4 @@ VOLUME ["/certs"]
 
 CMD /start.py
 
-HEALTHCHECK CMD curl -f -L http://localhost/ || exit 1
+HEALTHCHECK CMD curl -k -f -L http://localhost/health || exit 1