Improve OpenVPN module

Created by: SunilMohanAdapa

After pull request #269 is committed, improve OpenVPN support:

• Run as non-root
• Switch to using elliptic curve cryptography #1514 (closed) (Reduce to 2048 based on feedback)
• Add user authentication also
• Implement certificate revocation
• Better representation for remote server
• Add Manual page
• UI: Add toggle button