connection: `autoDecompress` option
1.21.0
Revert "connection: `autoDecompress` option"

This reverts commit 950a1c895164effc7b500f5c8b4053d8cba5bdec.
1.22.0
Disable header compression by default in clients.

It is known that header compression leads to information leak.
Header compression is still enabled in servers. See the Google Groups
forum below for related discussions.

See:
http://en.wikipedia.org/wiki/CRIME_(security_exploit)
https://code.google.com/p/chromium/issues/detail?id=139744
https://bugzilla.mozilla.org/show_bug.cgi?id=779413
https://groups.google.com/d/msg/spdy-dev/6mVYRv-lbuc/qGcW2ldOpt8J