Use 'resources' instead of 'sources'

According to the buster-configuration documentation for sources (at "http://docs.busterjs.org/en/latest/modules/buster-configuration/"): 

"sources: Source files to load in script tags in the browser." 

But script tags duplicate what requirejs already does to load source in tests whenever it encounters a "define()" block.  So, while using 'sources' works, it's a bit of a misdirection in terms of communicating intent.  I offer that it's better to use the 'resources' field, which seems more specific to this use case.  I've updated the configuration and tested that the tests run as before.
Merge pull request #1 from jaabio/patch-1

Use 'resources' instead of 'sources' because AMD modules should not be loaded by script tags