getColumnWidth(id) {
    let total = this.tableWidth;
    let percentage = this.getSavedPercentage(id);
    if (isNone(percentage)) {
      percentage = 1 / this.columnSchema.length;
    }
    return floor(total * percentage);
  }
Returns a specific column's width. This value could either
be calculated or retrieved from local storage cache.

@method getColumnWidth
@param {String} id The column's id
@return {Number}   The column's width