Workspace: use waitTillListening in start()

Replace setTimeout in `Workspace.start` with `waitTillListening` call
to prevent the situation when the process needs more than a second
to boot and start the HTTP server.
fixup! fetch host:port before spawn, fix tests
squash! use unique port for start/stop tests

Implement a helper `given.uniqueServerPort` that configures the server
facet to use a port number that is different in each process.

Use this new helper in start/stop tests to prevent collisions on the
build server.

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Bring back increased test timeout.
fixup! move wait-till-listening to regular deps
Merge pull request #150 from strongloop/feature/wait-until-started-process-is-listening

Workspace: use waitTillListening in start()