Add USE_SHELL setting so compressor binary on windows system PATH can run

docs/compressors.rst

@@ -264,3 +264,15 @@ Add it to your settings ::
 
   PIPELINE['CSS_COMPRESSOR'] = 'jam.compressors.JamCompressor'
   PIPELINE['JS_COMPRESSOR'] = 'jam.compressors.JamCompressor'
+
+
+Use Shell to run compressor binary (Windows)
+============================================
+
+If you have a compressor binary such as Yuglify installed globally using NPM on windows, you can enable ``'USE_SHELL'``,
+that way it just searches your PATH.
+
+Then in your settings you could use: ::
+
+  PIPELINE['USE_SHELL'] = True
+  PIPELINE['YUGLIFY_BINARY']: 'yuglify'

pipeline/compressors/__init__.py

@@ -244,7 +244,7 @@ def execute_command(self, command, content):
                 argument_list.extend(flattening_arg)
 
         pipe = subprocess.Popen(argument_list, stdout=subprocess.PIPE,
-                                stdin=subprocess.PIPE, stderr=subprocess.PIPE)
+                                stdin=subprocess.PIPE, stderr=subprocess.PIPE, shell=settings.USE_SHELL)
         if content:
             content = smart_bytes(content)
         stdout, stderr = pipe.communicate(content)

pipeline/conf.py

@@ -78,6 +78,8 @@
     'LESS_BINARY': '/usr/bin/env lessc',
     'LESS_ARGUMENTS': '',
 
+    'USE_SHELL': False,
+
     'MIMETYPES': (
         (b'text/coffeescript', '.coffee'),
         (b'text/less', '.less'),