Jolokia JMX REST integration

Integrates Jolokia (JMX via REST) into the OSv http server.
The library itself is loaded on demand in a side-by-side classloader,
and requests (rudimentarily defined in the swagger json) are forwarded
via JNI calls from the http server to be dispatched inside Jolokia.

Includes some helper library code to easy JNI usage, as well as trying to
ensure proper synchronization with the JVM lifecycle. As in ensure we either
run a request (with JNI attach) or we don't. JVM shutdown combined with
a request could otherwise cause crashes.

Signed-off-by: Calle Wilund <calle@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Merge branch 'jolokia'

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Conflicts:
	modules/httpserver/module.py