Javadoc tweaks

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1529282 13f79535-47bb-0310-9956-ffa450edef68
HTTPCLIENT-1412: SystemDefaultCredentialsProvider doesn't specify RequestorType.PROXY for proxy authentication requests

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1529291 13f79535-47bb-0310-9956-ffa450edef68
HTTPCLIENT-1413: Fixed divide by zero error in FutureRequestExecutionMetrics

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1529295 13f79535-47bb-0310-9956-ffa450edef68