QGIS 2.18 adds the ability for users to set whether a user created color scheme should show up in the color button drop-down menus. This setting is controlled through the color picker dialog, on the lists tab. Just add a new color scheme, then from the scheme menu tick the new "show in buttons" option. It's a handy shortcut if you have sets of common palettes and want them to be instantly available through the color menu.