option multipleWidth with more flexibility

[ltdeta]

Please do not set the multipleWidth option statically to px

this.$drop.find('.multiple').css('width', "".concat(this.options.multipleWidth, "px"));

It would be better to pass the unit with in the option

this.$drop.find('.multiple').css('width', this.options.multipleWidth);

example1: $.multipleSelect( { multiple: true, multipleWidth: '230px' } );

example2: $.multipleSelect( { multiple: true, multipleWidth: '100%' } );