feat($compile): isolate scope properties in controller context via controllerAs

It is now possible to ask the $compiler's isolate scope property machinery to
reference properties by their isolate scope.

The current syntax is to prefix the scope name with a '@', like so:

    scope: {
      "myData": "=someData",
      "myString": "@someInterpolation",
      "myExpr": "&someExpr"
    },
    controllerAs: "someCtrl",
    bindtoController: true

The putting of properties within the context of the controller will only occur if
controllerAs is used for an isolate scope with the `bindToController` property of the
directive definition object set to `true`.