Support DataDog Reporting.
Directory update bug fix.
Fix for federated message flow to support source IDs.
Disallow registration from clients registered on another relay.
Bump version to 0.6
Support for querying PreKey meta-information.
Bump version to 0.7
JSON metrics reporting.
Add contacts histogram and directory controller test.
Bump version to 0.9
Add host system metrics.
Write identity key into 'account' object.

This is the beginning of a migration to storing one identity
key per account, instead of the braindead duplication we're
doing now.  Part one of a two-part deployment in the schema
migration process.
Bump version to 0.10
Schema migration for identity keys.
Bumping version to 0.11
Treat account object as authoritative source for identity keys.

Step 3 in migration.
Bumping version to 0.12
Final migration step, remove identity_key column from keys table.
Bump version to 0.13
Upgrade to dropwizard 0.7.