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 "ngAttr", "ng-attr-", "ng:attr:" or "ng_attr_"  so it will
be set only when the binding is done. The prefix is then removed.

I.e:
<svg>
  <circle ngAttrCx="{{cx}}" ng-attr-cy="{{cy}}" ng:Attr:r="{{r}}"></circle>
</svg>

Closes #1925