#29 Remove code duplication for env. variables merge. Extract to a new function.
#29 Merge 'deploy.[ENVNAME].env' values to the environment variables object.
#29 Minor code cleanup.
#29 Create a test for the new functionality. Fix a found bug.
#29 Comment amendment.
#29 Additional check for envName
#29 Change priority: lowest is deploy.dev.env, then app.env, and highest is app.env_dev. Update docs. Update sample ecosystem.json when doing `pm2 ecosystem`.
Merge pull request #847 from koresar/development

Allow env vars per each ecosystem's deploy