Feature/configurable assets attributes

[rindeal]

Added ability to add attributes to the generated assets' html
Example

{{ assets.css({'class': ['some', 'classes']}) }} === {{ assets.css({'class': 'some classes'}) }} 
{{ assets.js(['async']) }} === {{ assets.js({'async': 'async'}) }}

[w00fz]

Nice!

[rindeal]

Thanks

[w00fz]

Tested and looks great. Thank you.

If you feel like, would be nice if you could also add the this addition to the learn docs (can see it live here)

[rindeal]

I'll try to find time to add it before the release, but I prefer code over text...

[rhukster]

don't we all! :)