Support remote containers on remote hosts

Remote container support is currently limited to separate JVMs with a shared filesystem.

This change allows containers on remote hosts to be supported by serving bundles to be installed in the container using a simple (single class) HTTP server. We've been using this approach in our Arquillian fork since 2012 and it's worked well.

Also updated docs to include current set of containers, and to note that the Apache Karaf remote container actually works with any OSGi Enterprise JMX enabled container (we use Apache Aries JMX in an Equinox container).