nether internal logic follow up

nether internal logic follow up

- mark is always int32_t and -1 means that
  no packet marking is done, and the packet
  should go through normal iptables rules

- when not copying packet, address and port
  are zeroed to indicate this in logs

- the builtin privilege for cynara is used
  unless specified in the policy file or
  on the command line NETHER_CYNARA_INTERNET_PRIVILEGE

- new command line parameters for cynara
  backend are "policy" - defines the path
  of the policy file  and "privname" - defines
  the default privilege to use when doing
  cynara checks

Change-Id: I1b4a91685af7f27fff162317a63e15a2d1b7319c
Signed-off-by: Zbigniew Jasinski <z.jasinski@samsung.com>