Updated vim-airline

This update adds the new tabbar stuffs.
Changed airline separators to non-arrow characters

This still looks fancy without implying a hierarchical relationship
between adjacent items.
Revert "Removed autocommand to restore the last cursor position"

This reverts commit 793a027743844af598e2dd99c3b699834122a3ee.

Vim doesn't restore the cursor position automatically. (As I previously
thought. Perhaps I was using a global config and didn't realize.) Vim
does save the cursor position as a mark, however, which we can jump to.
Renamed mapping to "diff middle"
Added mappings to open Fugitive status and commit windows in a new tab
Added Salt minion helpers: __grains__, __pillar__; Jinja template test
Fixed number/relative number toggle mapping
Renamed 'ps' alias to not clobber regular ps command
Removed pre-Vim tabs kludge mappings & split movement shortcuts

The pre-native tabs is sufficiently old now and I find I never use the
shortcut mappings to switch between split windows. (I do find I
accidentally use the left mapping quite often when hitting ctrl-l to
redraw the screen which is annoying.)