Created JS core project
Added more functionality and tests
Added tests for Snowplow unstructured events
Added tests for ad-related unstructured events
Added custom contexts to all events
Added test for trackEcommerceTransactionItem
Added tests for environment name-value pairs
Created index.js
Added .npmignore
Added optional callback argument to apply to every payload
Added test for callback
Added addEnvironmentDict method
Updated payload test to use self-describing JSON
Updated order of ecommerce method arguments to match those of the JS Tracker
Added README.md
Renamed snowplow-core to snowplow-tracker-core
Renamed environment to payloadPairs
Updated README with new method names
Added license
Updated license in package.json
Added setBase64Encoding method and contexts test