Enterprise form required fields span

Added red asterisks with slightly bigger font size.

This commit uses the same pattern as the rest of the project, `span.required *`.

Original text of BugHerd #454:
Need to denote fields that are required (I am noting just these fields with bugherd b/c I'm assuming they're required). Don't just use color - remember to account for those that are color blind. Also try to use something a little larger than an asterisk (*) in the normal font size -- that may be too small for tired or older eyes to see easily. (An asterisk with a larger font size that is also red = an easy (if boring) indicator).