Sourcemap paths are incorrect

[DerekTBrown]

Bug, feature request, or proposal:

Bug

What is the current behavior?

@jelbourn in publishing the latest version to npm, it seems you left your own project path in the javascript map files. Consider the following excerpt downloaded directly from npm:

node_modules/@angular2-material/button/button.spec.js.map:

{"version":3,"file":"button.spec.js","sourceRoot":"","sources":["../../Users/jelbourn/material2/tmp/broccoli_type_script_compiler-input_base_path-ln

[jelbourn]

@hansl we fixed this once before but it seems like it's happening again.

[jelbourn]

Still a convenient issue to track that we don't have an source maps in the latest release.