Define simple healthchecks for simulators

- currently containers are healthy if they have successfully started
their Http servers thus simple endpoint at /healthcheck is sufficient
- to enable docker healthcheck we need to add `curl` to docker images
- http_proxy needs to be provided for docker to be able to build images
behind proxy

Closes ONAP-695

Change-Id: I02f0b8cc2732713b5307dbc34ba604d8185b74fc
Signed-off-by: fkrzywka <filip.krzywka@nokia.com>
Issue-ID: DCAEGEN2-601
6 files changed