Angular dependency

Thanks for the great directive! :+1: 

Would you consider to be less strict on the angular dependency? Using newer angular versions and bower as scaffolding:

```
Unable to find a suitable version for angular, please choose one:
    1) angular#~1.0.6 which resolved to 1.0.8 and has angular-qrcode#1.0.0 as dependants
    2) angular#v1.2.0-rc.2 which resolved to 1.2.0-rc.2
```