"app/" in stack traces was an artifact of how we lay out files in the
built server, not how the source files are laid out, and isn't actually
as good as just using the source file name. Slava improved this on this
branch by just using the real file name. So the test (newly merged from
devel) needs to be improved to match.
While we're at it, let's test for filenames in a package.
- Uses Ben's meteor-babel npm package that has a default config
- From a checkout, uses the meteor-babel/register module and compiles at runtime
- When meteor-tool is published, precompiles the files
- Adds tests to make sure source maps work everywhere
