add init support for centos7

[nathangoulding]

The setup script is not working on a CentOS 7 machine:

[root@localhost tink]# ./setup_with_docker_compose.sh
grep: /etc/network/interfaces: No such file or directory
This is network interface
grep: /etc/network/interfaces: No such file or directory

It should also have set -e to stop execution if there are errors.

[parauliya]

Hi @nathangoulding , This issue has been addressed in PR #62 which is for the issue #49 .