Log Message:
Update ruby-httpclient to 2.8.3.

Changes in 2.8.3			2016/12/8

Bug

* Avoid frozen string errors on Ruby 2.3 - fixed by RJ Walsh #336
* SSL timeouts not working on JRuby - fixed by Dave Golombek #341
* Do not reset SSL connection if unnecessary - fixed by Dave Golombek #344
* Ignore text around PEM file in JRuby fixed by Scott Kolb #352

Changes

* Add HTTPClient#tcp_keepalive= for enabling TCP keepalive. false by default. #350