Introduce Service Instance netns command config parameter

Change-Id: I31128b1ea871b90340ebdb3766a37ce4d075a887
Fix typo of the config parameter

Change-Id: I327ce08c28fc23d97189ba45f73ad9845166b26c
Add netns_command in the main file

Change-Id: Ib83488b3d186c5610b69ee9b6e7509367d3f762c
Merge pull request #3 from safchain/param_netns

Introduce Service Instance netns command config parameter