Add Apitally to plugins.json

[itssimon]

trafficstars

Added Apitally to the list of plugins under Logging/Metrics.

Apitally is a simple API monitoring and analytics tool with an official hapi plugin.

Repo: https://github.com/apitally/apitally-js Docs: https://docs.apitally.io/frameworks/hapi Website: https://apitally.io/hapi