Filter getVCPENetworkById and getAllVCPENetworks with AclManager.

getVCPENetworkById launches an exception if access to specified vcpe is denied for currently authenticated user.
getAllVCPENetworks filters the list of returned VCPEs garanting that only vcpes currently authenticated user has acess to are returned.

These methods make uso af ACLManager to check desired resource is accessible for currently authenticated user.
VCPENetworkManager small refactor: create service getters and use them in this class.

Also avoid ActivatorExceptions being propagated, they are turned into VCPENetworkManagerExceptions in those getter methods.

This patch also structures getVCPENetworkById in a set of calls adding one single functionallity each.
Merge pull request #610 from isartcanyameres/feature/filter-getvcpe

Feature/filter getvcpe