Update to httpclient 4.5.5 and httpcore 4.4.9 for HTTPCLIENT-1655
Update to httpclient 4.5.5 and httpcore 4.4.9 for HTTPCLIENT-1655

Versions older than 4.5.1 were incorrectly handling connection
termination, sending a RST instead of the proper FIN ACK sequence.

signalfx/signalfx-java,signalfx/signalfx-java,signalfx/signalfx-java