tooltip support in schema properties

[Kanabanarama]

• Move 'tooltip' under options since it isn't a standard JSON Schema keyword

{
  "type": "string",
  "minLength": 4,
  "options": {
    "tooltip": "This is a tooltip"
  }
}

• Instead of adding another argument to getFormControl, I would create a new theme function addTooltip that takes a DOM node as an argument. That way it can be reused elsewhere and it will be easier for themes to override.

this.control = this.theme.getFormControl(this.label, this.input, this.description);
this.theme.addTooltip(this.control, this.tooltip);

• For bootstrap3, add data-toggle="tooltip" to the element (http://getbootstrap.com/javascript/#tooltips)