Changes

ttcn3-epdg: Run osmo-epdg with CAP_NET_ADMIN

This will be needed since soon osmo-epdg will start creating tunnel
devices througth gtp_u_kmod, which requires CAP_NET_ADMIN, plus it will
need probably need to set up local IP addresses.

Change-Id: I48eea0e8d7969cc0a3ad2ed08f696decf064c474