Event Serializer.

[krisajenkins]

Fixes #59.

Note: I'm going to add event-deserializer to this PR, but I think it makes sense if it's mirror image of event-serializer. So my plan is to get feedback on one of them first, get it nearly ready, and then make the twin.

New Pattern Checklist

• [X] Pattern file name should follow docs/pattern-category/pattern-name.md
• [X] Create an on-brand diagram (https://docs.google.com/presentation/d/1Zf256Z6fBvre3uclIbmxXsDpnTIxiBX66b13pHbGIYc/edit?usp=sharing)
• [X] Implement ksqlDB or code example (not all patterns will have code, but highly desired)
• [X] Provide references
• [X] Validate hyperlinks
• [X] Spell check (e.g. using aspell)

[krisajenkins]

Review comments addressed, and deserialization is now in to match. Please re-review. :-)

[krisajenkins]

No problem.

[krisajenkins]

Fixes #60.