[TORQUE-997] Dependency injection: allow configuration of directories where injectors will work

Allows to customize (override) the default paths where injection scanner will look for files to inject to. Configuration is done per-application  in application descriptor. For example:

TorqueBox.configure do
  injection do
    path "directory"
  end
end

TorqueBox.configure do
  injection do
    path ["directory1", "directory2"]
  end
end
Merge remote-tracking branch 'goldmann/TORQUE-997-dependency-injection-custom-paths' into 2x-dev