Update event schema

[mpothier]

Description

• Updates the event schema to version 2.2 for keystroke and select events. Added some validation to payload constructions to ensure server compatibility.
• Enable logging with filters and localGeocoder results mixed in. This is made possible by tagging a _source for Mapbox results to distinguish from client-added results.

• briefly describe the changes in this PR
• write tests for all new functionality
• run npm run docs and commit changes to API.md
• update CHANGELOG.md with changes under master heading before merging

[mmarkov]

lgtm;