Node.js agent v6.12.0

Improvements

• Updated guidelines and templates for contributing to the project.
• Updated SECURITY.md with coordinated disclosure program link.
• Upgrade async to v3.2.0. Special thanks to Yohan Siguret (@Crow-EH) for the contribution.
• Bumped @newrelic/native-metrics to ^5.3.0.
• Bumped @newrelic/aws-sdk to ^2.0.0.
• Bumped node-test-utilities to ^4.0.0.
• Bumped @newrelic/superagent to ^3.0.0.
• Bumps @newrelic/koa to ^4.0.0.

Fixes

• Fixes obfuscation of SQL queries with large data inserts. Special thanks to Tomáš Hanáček (@tomashanacek) for tracking down the issue and providing the fix.
• On failed instrumentation, prevent multiple requires from re-wrapping shims. Special thanks to Ryan Copley (@RyanCopley) for the contribution.