how to use call compass with the compass-support version?

I attempt to use `digitallyseamless/nodejs-bower-grunt-runtime:compass-support` into wercker for angularjs app.

Everything goes well except for `compass`. Where system stop at `/bin/sh: 1: compass: not found`

For more details I opened issue on [stackoverflow](http://stackoverflow.com/questions/33633135/how-to-use-digitallyseamless-nodejs-bower-grunt-runtimecompass-support-in-werck)
