Agent - 0.4.0

## [0.4.0] - October 23rd, 2019 - Adds admin endpoints for health, info and metrics - Adds requestId to logs and response header - Improves log integration with Optimizely SDK - Updates swagger spec to match current server implementation - Updates dependency version for the Optimizely SDK - Enhance webhook service configurability

https://github.com/optimizely/agent/releases/tag/v0.4.0