New method getHostsByHostname

  - add to facilities managers (api,bl,impl)
  - add to rpc (facilitiesMethods)
  - special behavior for facilityAdmin (remove all hosts from facilities
    which this principal has not in authorized facilities)
Merge pull request #513 from stavamichal/getHostsByHostname

New method getHostsByHostname
Fix for method getHostsByHostname

 - problem with authorization if PerunAdmin is also FacilityAdmin
Merge pull request #514 from stavamichal/fixForGetHostsByHostname

Fix for method getHostsByHostname