Release v1.1.6

• [Brian Menges] - Add CONTRIBUTING.md
• [Brian Menges] - Revise README.md

Release v1.1.5

• [Brian Menges] - Update ami_map for GitHub Enterprise v2.6.3
• [Brian Menges] - Update ami_map for GitHub Enterprise v2.5.8
• [Brian Menges] - Update ami_map for GitHub Enterprise v2.5.7
• [Brian Menges] - Update ami_map for GitHub Enterprise v2.5.6
• [Brian Menges] - Change default ghe_version to 2.6.3