Simplified directive. Fixed problem when multiple flags were inserted in...

Hi. 
I was using your directive in my project and found an error when you used multiple span tags for flags.
The problem was that they did not render properly and they all would be with the last flag used.
The issue was that they were all sharing the same scope.

I have taken the liberty of simplifying / correcting your module and now each directive has its own scope.
As such, now it works with multiple flags.

Cheers