boBind directive issue

ex1.

```
<div bo-bind="value1 + value2 + value3 + value4"></div>
```

ex2.

```
$scope.jobs = [
    {id: 1, name: 'job1'},
    {id: 2, name: 'job2'}
];
$scope.jobStats = {
    '1': 'stats1',
    '2': 'stats2'
};
```

```
<div bindonce ng-repeat="j in jobs">
    <div bo-bind="jobStats[j.id]"></div>
</div>
```

do not work as expected;
