feat($compile): Allow late binding attributes

Sometimes is not desirable to use interpolation on attributes because the user agent parses them before the interpolation takes place. I.e:

```html
<svg>
  <circle cx="{{cx}}" cy="{{cy}}" r="{{r}}"></circle>
</svg>
```

The snippet throws three browser errors, one for each attribute.

For some attributes, AngularJS fixes that behaviour introducing special directives like ng-href or ng-src.

This commit is a more general solution that allows prefixing any attribute with "late:" so it will be set only when the binding is done. The prefix is then removed.

I.e:
```html
<svg>
  <circle late:cx="{{cx}}" late:cy="{{cy}}" late:r="{{r}}"></circle>
</svg>
```
Closes #1925