Allow module scripts to be found in raw mode.

The logic in src/org/plovr/raw.soy searches for the plovr
script based on the presence of the path '/compile' existing
in the script src.

In a reverse-proxy context, this test will fail.  Until I find a better
way, for now, also search for the first script matching module_%s.js.

An improvement here would be to incorporate the moduleOutputPath pattern
in the check, since this change will fail for module out path patterns
that stray from module_%s.js