Allow different unit conversions for JSON tabular output file

[JasonGlazer]

Issue overview

Currently, the normal tabular output file (often HTML) and the SQL file can have different unit conversions. One can be SI, and the other IP, for example. It would be good to extend this to the JSON tabular output options. This might be especially convenient for the createRPD output, which uses JSON and needs to be in SI. The infrastructure in the reports that generate the tabular outputs is already present but just not wired in for JSON.

Details

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• Platform (Operating system, version)
• Version of EnergyPlus (if using an intermediate build, include SHA)
• Unmethours link or helpdesk ticket number

Checklist

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• Defect file added (list location of defect file here)
• Ticket added to Pivotal for defect (development team task)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)