build.js fix(?), fixed greedy comments, and changed Jison dependency

Three commits for you.

The first fixes a bug where C-style comments were being too greedy and swallowing up code between them.
```
/* comment */ thisCode(isBeingSwallowed); /* comment */
```

The second changes the package.json dependency on Jison from `latest` to a concrete version number.  I believe a Jison upgrade broke something in the past, but I'm not 100% sure.  If you'd like to leave it as `latest`, I'm ok with that.

The third is a `build.js` change that changes how it executes other processes.  I was using a third-party module called `executive` which might be broken.  Now it's plain old Node.js `child_process.spawn`.