Stop flagging files with dots as having an extension.

Now, we look for a specific extension.  This could still be improved, a lot.
Refactor pattern-matching code out of findRequires and make it more reusable.
Sniff for AMD evidence when moduleType is unknown.
Allow onMatch callback to return false to terminate scanning.
Ensure that comboRx regexp is reset for each file.
Stop inferring moduleType by scanning bower.json.

This mechanism never actually worked except for cujojs project since we scan for the word "cujo" (as well as "amd", etc.).
Always succeed at providing a moduleType when instantiating.

We know that bower is 99.9% amd or globals atm, so we can reasonably pick one of these.