Verify env vars before create sample files

[tallesh]

This patch force node-lambda first look into env vars before create sampleFiles (context.json and event.json)

Previously, every time node-lambda run was executed, a event.json file was created even if the -j parameter was informed, for example after execute:

node-lambda run --handler test.handler -j test.json

The event.json file would be unnecessarily created and the test.json file would not be created. The same logic occurs if the EVENT_FILE var was defined.

To correct it, this code force node-lambda first look into env vars before create sampleFiles (context.json and event.json).

[DeviaVir]

@tallesh thanks for your contribution! Would you mind adding tests demonstrating it is now working correctly?

[tallesh]

@DeviaVir sure! I don't master javascript tests, but I will do some cases and commit again. Feel free for make comments and suggestions on my commits.

[DeviaVir]

+1 thanks @tallesh

[DeviaVir]

This has been added to 0.8.2 which has been released on NPM as the latest version, thanks again for your contribution! 🎊

[tallesh]

Great! :)