Make Metrics Reporters configurable via SPI

Adds a new `metrics` section to the Dropwizard `Configuration`,
permitting users to define `reporters`, based on `ReporterFactory`
implementations.

Any `EnvironmentCommand` will automatically add the configured metrics
reporters to its lifecycle.

Current implementations:

  * `console` - `ConsoleReporterFactory`
  * `csv` - `CsvReporterFactory`
  * `log` - `Slf4jReporterFactory`
Add documentation for metrics reporter factories.

Documentation has been omitted for fields and accessor methods whose
operation are obvious by their signature.
Allow permissive deserialization of all enums

When deserializing enum types, we should allow:

  * Whitespace in the value, which should be stripped out for parsing.
  * Lower-case characters, which should be converted to upper-case.

This makes using enum type in Configuration files more permissive and
less confusing.
Add tests for ReporterFactory implementations
Don't allow configurable Clock

Application-level metrics are highly unlikely to want a non-default
Clock implementation. Lets remove the Clock configuration and require
users to manually add those reporters to their service if they need
them.
Handle Exceptions during reporter initialization

Metric reporters are nice, but not critical. Lets not fail service
initialization in the event that an Exception occurs (e.g. a remote
service the reporter reports to is not responding).
Add GraphiteReporterFactory

Adds an optional dependency on metrics-graphite.
Add support for GangliaReporter configuration
Improve enum deserialization

  * No more reflection.
  * Dashes now permitted and replaced with underscores.
  * Tests refined so each one is testing only one thing.
Throw a JsonMappingException bad enum values
Add tests for Ganglia and Graphite
Add support for GangliaReporter prefix
Merge pull request #340 from nicktelford/feature/jackson-permissive-enum-deserializer

Allow permissive deserialization of all enums
Rename to FuzzyEnumModule.

I think that's probably easier to understand.
Update to Metrics 3.0.0-RC1.
Upgraded to Jackson 2.2.2.
Merge pull request #338 from nicktelford/feature/metrics-reporters-spi

Make Metrics Reporters configurable via SPI
Improve the error messages for enum deser.
Rejigger dw-metrics.

* Clean up the various classes.
* Flesh out GangliaReporterFactory a bit more.
* Add support for markers to Slf4jReporterFactory.
* Split out dw-metrics-ganglia and dw-metrics-graphite.
* Removed the reporters package.
Fix locale-dependent tests.

Closes #341.