Chat commands executed from API to room
Support sprintf style %s buckets in xargs commands

Example:

!complete does ie support | xargs echo %s? no, it is sucky

does ie support html5? no, it is sucky
does ie support css3? no, it is sucky
does ie support svg? no, it is sucky
does ie support media queries? no, it is sucky
does ie support ftps? no, it is sucky
does ie support png? no, it is sucky
does ie support canvas? no, it is sucky
does ie support @font-face? no, it is sucky
does ie support webgl? no, it is sucky
does ie support ttf? no, it is sucky

This is 1/2 of the fix for #191.