Change RegistryService to singleton, and add unit test

- Remove static from declaration of RegistryService (metrics)

Resolves: https://www.pivotaltracker.com/story/show/77113576
Minor code cleanup
Upgrading Metrics libraries to latest stable offerings from Dropwizard
Update clustering config based on ModeShape and Infinspan schema changes

Resolves: https://www.pivotaltracker.com/story/show/78230530
Merge pull request #455 from fcrepo4/DropwizardMetrics

Upgrading Metrics libraries to latest stable offerings from Dropwizard
Add error handling when Event userdata is empty/null.

Resolves: https://www.pivotaltracker.com/story/show/78467744
Simplify component scanning to the 'org.fcrepo' package

Resolves: https://www.pivotaltracker.com/story/show/78517974
Add fedora:object to federated filesystem directories

- Replace loop/flag logic with Guava one-liners

Resolves: https://www.pivotaltracker.com/story/show/70990124
Detect unregistered namespace prefixes

...and provide useful error messages in the UI.

Resolves: https://www.pivotaltracker.com/story/show/61500542
Code factoring for JcrPropertyStatementListener and RdfAdder/Remover

- Add unit test for FedoraTypesUtils

Resolves: https://www.pivotaltracker.com/story/show/71846066
Enable read-write operations on federated filesystem

- Depends on fix for MODE-2252 (https://github.com/escowles/modeshape/tree/mode-2252)
- Remove IT from connector project (because REST API transaction context is required for the tests)
- Re-enabled the REST API federation write tests
- Disable caching of generated properties

Resolves: https://www.pivotaltracker.com/story/show/70954532
Temporarily disabling repository object/byte counts
Re-Add repo-breaking test (fixed by MODE-2254)

Resolves: https://www.pivotaltracker.com/story/show/71234238
Merge pull request #463 from fcrepo4/disable-repoinfo

Temporarily disabling repository object/byte counts
Fix compiler error from previous commit
Add IT for preserving properties on federated filesystem moves

Resolves: https://www.pivotaltracker.com/story/show/70990730
Redirect to external content on GET of fcr:content

- Update IT to use federated datastream source for external content

Resolves: https://www.pivotaltracker.com/story/show/74627750