add the possibility to display html in the header

The fnLabel can be used to achieve this. 
According to what you have suggested I have added the following changes to the getLabel function and it shows the html that I return, so it is working for me.

Also is there a way to take out the sorting possibility from these columns?

Let me know if I missed something :) 
   'getLabel': function () {
        if(this.label != undefined){
            return _.isString(this.label) ? this.label : this;
        }
        else{
            return this.fnLabel();
        }
    },
Thank you for your help.