415548 migrate ProxyHTTPToSPDYTest to use HttpClient to avoid intermittent NPE
415548 migrate ProxyHTTPToSPDYTest to use HttpClient to avoid intermittent NPE part 2
merge ProxyHTTPSPDYConnection change with 9.1
cleanup import in HttpConnection
415548 migrate ProxyHTTPToSPDYTest to use HttpClient to avoid intermittent NPE part 2
416251 ProxyHTTPToSPDYConnection now sends a 502 to the client if it receives a rst frame from the upstream spdy server
416251 ProxyHTTPToSPDYConnection now sends a 502 to the client if it receives a rst frame from the upstream spdy server
fix merge issue
416321 improved test harnesses
416321 handle failure during blocked committing write
416321 handle failure during blocked committing write
Merge remote-tracking branch 'origin/master' into jetty-9.1

Conflicts:
	jetty-io/src/main/java/org/eclipse/jetty/io/AbstractConnection.java
	jetty-server/src/test/java/org/eclipse/jetty/server/HttpServerTestBase.java
	jetty-spdy/spdy-http-server/src/main/java/org/eclipse/jetty/spdy/server/proxy/ProxyHTTPSPDYConnection.java