TS/HM: removed TODO for already implemented test.
TS/HM: added HttpServerTest.testDontCompressRestMoreThanOnce

Needs to be whiteboxed, since behaviour is OS / Configuration
dependant and we don't want to assume too much.

The relevant assumption is that a request larger than 1 MB won't
fit into one socket.send(...).  The white-box part verifies that
by observing multiple socket.send(...) calls for one chunk of data.