Upgraded fluent-hc to 4.3.4 due to bug

This bug (https://issues.apache.org/jira/browse/HTTPCLIENT-1474) causes
an error to occur when POSTing to datadog using fluent static
Request.Post() method.
Removed unnecessary HttpPost field from HttpTransport
Merge pull request #5 from bazaarvoice/coursera-fluent-fix

Upgraded fluent-hc to 4.3.4 due to bug