Vim: add some more mappings to get out of insert mode
Vim: add some more mappings to get out of insert mode

I've been using `jj` for a while now (and incidentally it was hard to
type that), but going to also see what `jk` and `kj` feel like.

Signed-off-by: Wincent Colaiuta <c76ac2e9cd86441713c7dfae92c451f3e6d17fdc@wincent.com>

wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent,wincent/wincent