Remove force_minify flag for min/activity.js.

This has been deployed, so the current code is now properly
minified, and we don't need the force_minify flag any more.

(The flag is needed when you remove a JS file from JS_SPECS.)

(imported from commit 8b3c7ffdbc875011d59c2560034750f0077db616)

zproject/settings.py

@@ -404,7 +404,6 @@ JS_SPECS = {
         'source_filenames': (
             'third/sorttable/sorttable.js',
         ),
-        'force_minify': True,
         'output_filename': 'min/activity.js'
     },
 }