Automatically detect apps with less folders to setup lessc include-path

pipeline_settings.py

def get_less_static_dirs():
    """get static-directory paths for apps that have less files
    Assumptions:

    * You want any LESS files from apps in INSTALLED_APPS
    * You don't have LESS files in any extra folders in STATIC_DIRS (maybe I should fix that... always thought static_dirs was dumb)
    """
    app_modules = [import_module(app) for app in INSTALLED_APPS]
    maybe_less_static_dirs = [
        # For Django apps, __file__ should always be the path to __init__.pyc
        '{0}/static'.format(os.path.dirname(app_module.__file__)) 
        for app_module in app_modules
    ]
    return [
        path for path in maybe_less_static_dirs 
        if os.path.isdir(os.path.join(path, 'less'))
    ]

PIPELINE_LESS_ARGUMENTS = '--include-path=' + ':'.join(get_less_static_dirs())