Pass cwd when creating Packages.gz for deb

Creating Packages.gz with full path leads to corrupted
Filename attributes for every package, therefore apt wasnt
able to discover those packages

Example of Filename attribute:
 Filename: ./.build/repositories/ubuntu/glusterfs-server_3.5.2-4_amd64.deb

Related to blueprint cinder-neutron-plugins-in-fuel

Change-Id: Ie9699a92dd8bc53717b19e0d4b96df551d2e3b8d