Revert "VIm: switch from YCM+UltiSnips to neo{complete,snippet}."

This reverts commit 608ad2aafc458b7388f623aeed32b004eac608eb.
Fix UltiSnips and YCM integration (?)
Update credentials in gitconfig.
Set xrandr mode in xinitrc.
Vim: use dark background always.
Change appearance of xmobar