Revert "Vimrc change from tabs -> spaces"

This reverts commit 4352570195076fb3c1db8dc3138574518073429b.
Merge branch 'master' into tabs
Merge branch 'master' into tabs
Merge branch 'master' into tabs
Merge branch 'master' into tabs
Merge branch 'master' into tabs
Merge branch 'master' into tabs
Add vim-sleuth