remove blank section headers/footers from plain tables on iOS 11
remove blank section headers/footers from plain tables on iOS 11

This prevents blank section headers and footers from appearing on iOS
11 when setting the table view style to plain and there are no headers
or footers.

btanner/Eureka,btanner/Eureka,jpvasquez/Eureka,xmartlabs/Eureka,xmartlabs/Eureka,jpvasquez/Eureka