Correction for unequal handle text lengths

[dk-ok]

Line 502, _width() function:

//this._handleWidth = this.$on.outerWidth();
//CHANGE: _handleWidth computation to account for unequal text lengths
this._handleWidth = Math.max(this.$on.outerWidth(), this.$off.outerWidth());

Looks good and seems to work well. Issue is apparent on demo page "Off Text" example. Try text with no spaces.