Add custom Boruta HTTP headers

Add custom Boruta HTTP headers

This patch introduces two custom Boruta headers to replies for some REST
API functions:
* Boruta-Request-Status - contains current status of request. It is
  convenient to request HEAD on GetRequestInfo path to check only status
  of given request.
* Boruta-Request-Count - contains number of requests returned for
  Request List/Filter operation.
* Boruta-Worker-Status - contains current status of worker.
* Boruta-Worker-Count - conttains number of workers returned for Worker
  List/Filter operation.

Change-Id: I871c63058b2690bac50046f0dc500c795843b958
Signed-off-by: Maciej Wereski <m.wereski@partner.samsung.com>