Add a simple Stratum plugin for example purposes

[haobrien]

What's the problem you are facing?
Create a simple example of a plugin.

Describe the solution you're proposing
Create a simple plugin that logs Stratum events to the browser's console.

Additional context
This plugin can also be referenced in the Stratum README as an example for others.

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Note that any Stratum enhancements should add general functionality that applies to a broad range of users. If you're looking to add custom functionality to your specific application, we recommend creating or extending existing plugins when possible.

Next steps

• A maintainer will look over your request, and we'll help you flesh it and provide additional context/requirements as necessary.
• We welcome contributions from the community! If you're looking to contribute to this request, open a PR and connect it to the Github issue.
• Once your PR is approved and merged, we will close this issue and mark it as complete.

[erolunal]

@haobrien , this is an awesome contribution! Looking forward to the PR and incorporating the plugin into our instructional docs!