Ignore a missing mediacompress since its a local package.

[ci skip]

doc/web/hooks/__hooks__.py

@@ -1,16 +1,26 @@
 # -*- coding: iso-8859-1 -*-
+# Hook routines for the wok static site generator.
+# Note that mediacompress is a local module.
 import os
 
 
 def compress_javascript(config, output_path):
     """Minify JS files."""
+    try:
         from mediacompress import compress_js_files
+    except ImportError:
+        pass
+    else:
         compress_js_files(output_path, excludes=("*.min.js",))
 
 
 def compress_css(config, output_path):
     """Minify CSS files."""
+    try:
         from mediacompress import compress_css_files
+    except ImportError:
+        pass
+    else:
         compress_css_files(output_path)