Various changes investigating short reads

This is in relation to issue #425 where a report of a short_read still
happening in Linux (Debian) with GCC/Clang. This couldn't be reproduced
with an OpenSSL acquired via Homebrew on Mac OS X.

More tests would require specific OpenSSL versions, which may or may
not exhibit this issue.
Documentation updates on HTTP client

Fixes #116 for 0.11.1.
Merge pull request #428 from deanberris/0.11-devel-docfix

Documentation fixes & changes are trivial and the tests continue to pass.