Local JS library files are referenced as 'external' but should not be

Hi,
after updating advagg i ran in to troubles regarding my local mathjax lib, it could not be loaded/found. After some digging I found that mathjax tries to include the local lib as type => external and advagg does some magic because it thinks it's a url but it's not its a path.

I changed the type for the local lib to "file" this fixes the issue.