Revert "Add subroutines to remove Bit.ly data for story / controversy"

This reverts commit 5732494d79d29409abde2990dfc9b2de835a3818.
Fix case of form comments [ci skip]
Clarify the comment because we use the same form when both creating and editing a controversy
When controversy's date range gets increased, re-enqueue all controversy's stories for Bit.ly processing (assuming that only a single Bit.ly Gearman worker is running here so it won't run into race conditions)
Do some additional validation of a date passed as a parameter
Explain what will happen when a controversy's date range gets increased in the controversy edit page