Enable swipe-to-delete for tableViews in frontViewController

Small fix that lets you swipe-to-delete (left swipe only) in a tableView within frontViewController.

Works by returning `NO` in `-[SlidingScrollView gestureRecognizerShouldBegin]` when the slider is open and the translation is in the left direction. I'm not sure how backwards/forwards  compatible this is but it was the only way I could think of to enable swiping in one direction only.

Checking the frame of the scrollView is maybe not the best way of checking if the slider is open, but it seems to work and adding a delegate to ask the controller whether it was open seemed a bit overkill but easily added if preferred.