Adapted ExportAsJSON to work when run periodically
Adapted ExportAsJSON to work when run periodically

runPeriodic() is expected to be called on a timer. It searches the
specified Google Drive directory for the newest Sheets document and
processes it, storing the result in cache.

cityofsomerville/citydash,codeforboston/cornerwise,ejegg/citydash,cityofsomerville/cornerwise,patilav/citydash,wrightgd/citydash,cityofsomerville/citydash,wrightgd/citydash,cityofsomerville/citydash,cityofsomerville/cornerwise,codeforboston/cornerwise,wrightgd/citydash,patilav/citydash,patilav/citydash,cityofsomerville/citydash,wrightgd/citydash,ejegg/citydash,codeforboston/cornerwise,codeforboston/cornerwise,ejegg/citydash,patilav/citydash,ejegg/citydash,cityofsomerville/cornerwise,cityofsomerville/cornerwise