Add UseCompressionOnStreaming parameter

UseCompression is very useful on non-streaming request.
However, this will lead to the undesirable behavior on streaming
requests because WebResponse stream `buffers' messages and there are
no ways to determine how many messages `buffered'.

This commit adds UseCompressionOnStreaming option [default false]
to make streaming behavior desirable and predictable.
Merge pull request #83 from a4lg/feature/streaming-compression-switch

Add UseCompressionOnStreaming parameter