Properly closes http client to avoid single-connection conflict
Changes to better support Neo4j Desktop app

o Specifies service classes instead of packages to JAX-RS. Specifying
  packages requires JAX-RS to scan the classpath and doing that makes it
  more sensitive to environment changes... such as running the whole
  application inside a wrapped .exe file.
o Changes so that Configurator#getDatabaseTuningProperties() is always
  honored. This makes it much easier to pass in any Configurator implementation.
o JAX-RS ServletHolders gets created after all modules have registered all
  its service, since multiple modules might register at the same mount point.
  This problem became apparent due to the classes/packages change above.