Add plugins from Stratiform Digital

[mdial89f]

This Pull Request adds four plugins from Stratiform Digital

The plugins are:

• serverless-idempotency-helper: This plugin repacks lambda functions with washed timestamps to help make redeployments of the same code truly idempotent with no changes detected.
• serverless-iam-helper: This plugin helps set path and permissions boundary IAM settings in tough to reach places, like custom resources generated by other plugins.
• serverless-s3-security-helper: A simple plugin that sets sensible S3 bucket settings for all buckets in a stack.
• serverless-online: A plugin that uses the 'serverless deploy function' capability and chokidar to hot deploy lambda functions when changes are detected and stream logs to the console.

Thank you Serverless team!

[pgrzesik]

thank you @mdial89f 🙇

[mdial89f]

thank you @mdial89f 🙇

Hey @pgrzesik , thanks for merging, is updating this repository the path to getting plugins to show up on https://www.serverless.com/plugins ?

[pgrzesik]

Hey @mdial89f - yes, this serves as the source