Add non-xml/json files to src

[JohnHayford]

Extending issue #107 , it would be very helpful if I could add/replace any file type in the source, not just a xml or json file.

[mlynch]

The trick with this is the huge diversity of files we'd need to have some parsing support for to correctly modify. It's not likely to happen but I can see adding some other kinds of files based on popularity