Only accept bindinghandlers for the correct element type(s)

**Current behavior**
There are no limitations on where a bindinghandler is allowed to be used.

**Expected behavior**
`<span data-bind="value: x">` should not be allowed, since the bindinghandler 'value' should only be used on `<input>`, `<select>` and `<textarea>`
Another example is the bindinghandler 'allowValueUnset' that is only applicable to `<select>`-elements.