Fixing a compile error caused by an interface's signature change.
Upgrade to Jersey 2.11 and HK2 2.3.0-b10
Get rid of reflection-based monkey-patching of HK2

Instead of trying to override hard-coded defaults in the Injections class,
now the standard Java SPI (ServiceLoader) is being used. The required
Injector instance is created and held by the new GuiceInjectorHolder class
and used by Graylog2ServiceLocatorGenerator.