Documentation improvements

Here's some fixes to existing documentation:
1. Fixed nasty error in 'formatter' property of workers. There should be 'recorder', not 'proxy'.
2. Added example of minimal necessary config to run tests. Currently, it gives you a wrong idea that you should but a lot of properties with ~ in order to run the thing. It does the reverse thing, since you should pass the task name or not point that property at all.
3. Added some more description for compression property, since there's no way to guess why should somebody to turn it on.
4. Added better defaults handling in client and workers constructor.

Hopefully, this fix will help somebody to avoid a wasted day of debugging :)