[#206](https://github.com/motdotla/node-lambda/pull/206)

- Fix default value of EVENT_SOURCE_FILE set ''
[#205](https://github.com/motdotla/node-lambda/pull/205)
- Removed event_sources.json
[#204](https://github.com/motdotla/node-lambda/pull/204)
- Add -S, --eventSourceFile option.
[#203](https://github.com/motdotla/node-lambda/pull/203)