Added ability to use optional foo.TIMESTAMP.js naming convention

The default is still the original `?rel=TIMESTAMP` configuration, if you don't include any options.

Now, you can include a second parameter of options, and if your options includes a position of "filename", the file will be formatted differently.

This is the same option found in https://github.com/shakyShane/grunt-cache-breaker

So now you can do:
```
cacheBreak(file, {position: 'filename'})
```