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
add contrib list
fix pom syntax
[maven-release-plugin] prepare release metrics-datadog-0.1.7
[maven-release-plugin] prepare for next development iteration
Rename package to com.codahale.metrics.datadog

To match style from
https://github.com/dropwizard/metrics/tree/v3.0.1/metrics-graphite
Updated metrics-core to 3.0.2 and jackson-core to 2.3.2

Follows same pattern as
https://github.com/dropwizard/metrics/blob/v3.0.2/metrics-graphite/src/main/java/com/codahale/metrics/graphite/GraphiteReporter.java
Refactored DatadogReporter for metrics-core 3.0.2
Refactored MetricNameFormatter and DefaultMetricNameFormatter
Updated/Refactored DatadogReporterTest
Added Datadog class for creating JSON/posting http request
Removed MockTransport/Transport/HttpTransport
Updated README