Update to add prefix configuration options like statsd

- Add the same options but underscore delimited instead of camelCase, where supported
  - legacy_namespace
  - global_prefix
  - prefix_counter
  - prefix_timer
  - prefix_gauge
- Default to new namespace structure as defined by https://github.com/etsy/statsd/blob/master/docs/namespacing.md
- Minor refactors to minimize code or reduce operations
- Add a few debug checks for print output
Merge pull request #4 from gmr/namespace_change

Update to add prefix configuration options like statsd