Use `Promise.guard` from `prfun`.

Change-Id: I4360aad9c4b23285e3a3e7f6328b8b48b87ee9d8
Unlimited listeners; disable the request pool.

This ensures that we are in control of our parallelism, and we don't
unexpectedly create deadlocks within the request pool.

Change-Id: Ied7a8e54c38c3adf81571409ece55bb2548258a5
Use `readable-stream` package for better node 0.8 compatibility.

This patch also ensures that images are fully written and the stream
closed before resolving the promise with their filename.

Change-Id: Id6498397e359a9bed5eeee7b30648931508db201
Make travis more patient.

The bundler can be slow; emit verbose output to ensure that builds
don't time out prematurely.

Change-Id: I966f6c21ec28591374a86b6d2f89ada47a498a8d
HACK debugging travis

Change-Id: I92315b9b435cbbc2aa4d6fb7a500df766d5ebce3