More resilient hostname resolution

- Resolve hostname lazily if present. This will allow graceful handling
  of DNS changes if the VM is configured to do so.
- Add convenience constructor to StatsD so consumer doesn't have to
  instatiate the InetSocketAddress directly.
- Update quickstart directions in the readme to reference the
  convenience constructor.

	modified:   .gitignore
	modified:   README.md
	modified:   metrics3-statsd/src/main/java/com/readytalk/metrics/StatsD.java
	modified:   metrics3-statsd/src/test/java/com/readytalk/metrics/StatsDTest.java