Ignore bundler config.
Pass source file name to coffee compiler.

The compiler populates the source map’s `sources` array with this name
so we can map the compiled js back to its original coffee file.
Add source map test fixtures.
Compose minified map with original source map.
Combine all source maps in bundle.
Add initial source map for engines to use.
Test source maps.
Add source-maps directory to expected output.
Add metadata to test hash.
Return bare js if no source map is created.
Merge pull request #612 from dgraham/coffee-script-sourcemap

Pass source file name to coffee compiler.