Update Docker make file

- Include PIP proxies.
- Add docker compose targets.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/task_manager/classes.py

@@ -188,6 +188,10 @@ class Worker(object):
     def all(cls):
         return cls._registry.values()
 
+    @classmethod
+    def get(cls, name):
+        return cls._registry[name]
+
     def __init__(self, name, label=None, nice_level=0):
         self.name = name
         self.label = label