The `attr` object was only shallow copied which caused all observers to be shared.
Fixing similar issue in ng-* boolean attributes as well as ng-src and ng-href.
Breaks angular.fromJson which doesn't deserialize date strings into date objects.
This was done to make fromJson compatible with JSON.parse.
If you do require the old behavior - if at all neeeded then because of
json deserialization of XHR responses - then please create a custom
$http transform:
$httpProvider.defaults.transformResponse.push(function(data) {
// recursively parse dates from data object here
// see code removed in this diff for hints
});
Closes#202
