Add generic plugin transformation ability

[jbeemster]

• Adds both a short & long running process hook
• Short running caps at about 500 messages / sec
• Long running caps at about 8-9k messages / sec

Example scripts included!

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The interface requirements:

1. The plugin should "read" from "stdin" -> each message input will be newline delimited and the reader should process on finding a newline
2. The plugin must strip the newline and then base64 decode the message
3. The plugin must re-encode the transformed result in base64
4. The plugin must always send a value on both stdout & stderr (even if stderr is just an empty string)

The sample bash scripts should illustrate this flow!