feat(NodeAttrs): Node attributes don't get initialized by NodeAttrs when

setting up observing.

In case an element does not have an attribute set for a property defined
in NodeAttrs that property is not automatically initialised. Properties
that are initialised have to be set either using "name" or "ng-name"
attribute. For example:

```
  <div test foo="bar"></div>
```

will cause ElementBinder to register observer (which will in turn cause
initialisation) on property foo (of the directive) to bar, but if we try
using

```
  <div test></div>
```

foo property will not be initialised.
Unused variable `value`?