Fix a bad interaction with lusty-juggler and vim-endwise.

It turns out that lusty-juggler monkey with your mappings, and fails to
preserve the "<script>" tag added by vim-endwise for "<CR>".  So this
implements a roundabout way of determining whether or not the tag needs
to be added.
Merge branch 'fix-lustyjuggler-endwise-interaction' of https://github.com/jszakmeister/vimfiles