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:

<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
attributes 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:
<svg>
  <circle late:cx="{{cx}}" late:cy="{{cy}}" late:r="{{r}}"></circle>
</svg>

Closes #1925