Fixed issue django-compressor#26 - Added cssmin filter.

Author: jezdez

compressor/filters/cssmin.py

@@ -0,0 +1,15 @@
+from compressor.filters import FilterBase, FilterError
+
+class CSSMinFilter(FilterBase):
+    """
+    A filter that utilizes Zachary Voase's Python port of
+    the YUI CSS compression algorithm: http://pypi.python.org/pypi/cssmin/
+    """
+    def output(self, **kwargs):
+        try:
+            import cssmin
+        except ImportError, e:
+            if self.verbose:
+                raise FilterError('Failed to import cssmin: %s' % e)
+            return self.content
+        return cssmin.cssmin(self.content)