replace non-portable 'echo -n' utilisation with simple 'awk' statement
Update py-webassets to 0.9.

0.9 (2013-10-25)
    webassets now support Python 3, and drops support for Python 2.5.

    - Filter for Closure Soy templates (Michael Su).
    - less filter can output source maps (Riccardo Forina).
    - Support .pyc only deployments (Mike C. Fletcher).
    - Jade template filter (Roshambo).
    - YAMLLoader improvements (incl. Cédric Reginster).
    - The gzip filter was removed.
Updated www/py-webassets to 0.9.