don't ignore boolean values in flushToDOM

[lazychip]

Description:
flushToDOM is not working for boolean values
eg: if you flushToDOM visible component it won't work for false value
This is piece of code that has the problem

flushToDOM: function (isDefault) {
    var attrValue = isDefault ? this.data : this.attrValue;
    if (!attrValue) { return; }
    window.HTMLElement.prototype.setAttribute.call(this.el, this.attrName, this.stringify(attrValue));
},

Changes proposed:
My suggestion to add a boolean check for the attrValue

flushToDOM: function (isDefault) {
    var attrValue = isDefault ? this.data : this.attrValue;
    //  don't ignore boolean values
    if (!attrValue && typeof attrValue !== 'boolean') { return; }
    window.HTMLElement.prototype.setAttribute.call(this.el, this.attrName, this.stringify(attrValue));
},

[ngokevin]

Thanks!