Support gzip with encoding on node pre-v0.9.4

setEncoding was added to zlib streams in joyent/node@9b5abe5 (v0.9.4 and
later).  In order to support encoding and gzip together on earlier
releases, pass the data through an additional Stream which decodes the
data using the stringstream module.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>
Update changelog

Command used (github-changes v0.0.11):

github-changes \
  -o mikeal -r request \
  -a -v -f CHANGELOG.md \
  --use-commit-body
Fix https://null/ in changelog

See lalitkapoor/github-changes#36
Merge pull request #953 from LoicMahieu/master

Add async Content-Length computation when using form-data
Merge pull request #960 from kevinoid/gzip-encoding-pre-v0.9.4

Support gzip with encoding on node pre-v0.9.4
Merge pull request #963 from nylen/update-changelog

Update changelog