Add js_type config option (#59)

[Thomva]

I have added a js_type to the config.

[mrtimbrook]

Thanks for doing this. Is there a way we can work the type into the assets array so we're not setting the same type for all assets? It would need to support both array and string.

[Thomva]

Hi, sorry for taking so long to respond. I have updated the code. It now checks if the js asset has a type, and if so, it uses it in the script tag. I have also updated the README. Can this PR be reopened, or do I create a new one?