Fix my eval shortcuts in elisp mode

Now ex evals the surrounding form, and es evals the current sexp
Turn on autopair mode for css
Use gfm-mode for markdown

The immediate benefit for me is that underscores no longer trigger italics.
Background color snippet
Make the color used to highlight the current line less blatant
Configuration for window splits
Highlight the line the cursor is one
Make C-w and C-h work in the open file prompt
Don't prompt to close nrepl connections when exiting emacs
Fix typo in css hook

These autopairing modes really aren't great, however. They need some
tuning. I really only want help for indenting brances.
Fix name of ruby mode hook