Investigate improvements for working behind a proxy

[jesse-gallagher]

The main download mechanisms of the runtime should obey the http.proxyHost/etc. Java properties, but I don't know if those account for authenticated proxies.

You can use java.net.Proxy explicitly in HTTPURLConnection, so it may make sense to add configuration options for the outgoing proxy, or maybe there are settings in the names.nsf that I can look up.

Failing that, it would be good to document the filesystem layout of downloaded JVMs and Liberty instances, since they can be pre-populated to have the runtime skip the download. This wouldn't cover the CORBA download from the dominoApi extension, however - that may require either additional special handling or pre-population during the Maven build.

[jesse-gallagher]

It'd probably also be good to have an option to store these various artifacts in an NSF, which would be both useful for clusters and helpful for explicit management.