[Issue #241] Set HTTPBodyStream for streamed request

Signed-off-by: Mattt Thompson <m@mattt.me>
Update README.md

Fix "Operand of postfix '!' should have optional type" by removing extraneous `!` after `URL`
Merge pull request #247 from nsarno/patch-1

Update README.md
Compose percent-encoded query from percent-encoded components
Tests for URL with precomposed query
Merge pull request #249 from sunnycows/master

Compose percent-encoded query from percent-encoded components
Adding POST request JSON response test
Merge remote-tracking branch 'upstream/master'