[CC-1328] Custom cookbooks for monitoring/alerting of EC2 credit balances

[jfuechsl]

Description of your patch

Add a custom cookbook which sets up monitoring and alerting for EC2 CPU credits and IOPS burst credits for all attached EBS volumes.

Recommended Release Notes

See "Description of your patch"

Estimated risk

Medium. It is a custom cookbook and therefore not included by default. However, when included, it touches the core collectd configuration which is a core component.

Components involved

collectd, python3 (requests, boto3), /engineyard/bin

Description of testing done

Booted an environment with the custom cookbooks uploaded.
Checked if the environment works.
Checked if the metrics get reported.

QA Instructions

Test with different cluster configurations and instance types.
Test with load testing tools (cpu and disk) and check if alerts are triggered and reported properly.
Test upload of custom chef for existing environments.

[dvalfre]

@jfuechsl iiuc the PR pushes a change to the core recipes, right? no longer needed then to include it as a custom recipe?

[jfuechsl]

@dvalfre Correct, this is now part of the core recipes (collectd). Once we merge this it is available to everyone.