review and revise network dependent and independent tests

Whilst working on JAL-4688 several tests were observed to fail unexpectedly when http proxies were not properly configured for the test runner. We need to identify and delouse all tests failing when http proxy config is broken, to either fix problems or move the test to the network suite.

1. suggest the propagation mechanism that sets the JAVA_TOOL_OPTS for the test runner is made conditional for the http proxy settings so network connections can be "disabled" in our isolated build environment.
2. spend some quality time decoupling the various network dependent operations from functionality being tested so that those that shouldn't need a network connection can actually pass.
3. Create a new CI task that runs network suite tests only. This should either run periodically or when a new build is being published - not as a routine part of daily dev work.