Fixes data-colors bug in HTML5 configuration

Before the fix, to set the plate color (plate is used as exemple, any
        data-color property would fail), it was necessary to declare

    data-color-XXX-plate = '#aaa'

After the fix:

    data-color-plate = '#aaa'

As the docs suggest.

gauge.js

@@ -929,7 +929,6 @@ domReady( function() {
 									}
 								}
 								else {
-									cfgProp.shift();
 									cfgProp.shift();
 									config.colors[toCamelCase( cfgProp)] = attrValue;
 								}