v1.7.0

• Merge pull request #26 from Sleavely/http-keepalive 45c8bd8
• Mention HTTP keep-alive in README 85f0587
• Automatically enable HTTP keep-alive unless user supplies own HTTP Agent 14e2dd4
• Tweak TS definition imports so client options are correctly shown 78d6e5a

v1.6.0...v1.7.0