! build: bumped dependencies

- Updated spray-json 1.2.6 -> 1.3.0; this update has binary
  incompatibilities as described here:
  https://github.com/spray/spray/issues/932
- Updated newrelic 3.1.0 -> 3.11.0.
- Updated akka 2.3.3 -> 2.3.4.
- Moved scalaz-concurrent from a test dependency to a compile
  dependency.