Merge pull request #21 from audax/bugfix/sh-import

Fix import issues with the sh library

docs/credits/contributors.rst

@@ -20,6 +20,7 @@ Contributors (in alphabetical order)
 * Bertrand Bordage (https://github.com/BertrandBordage)
 * Brian E (brian@realize.org)
 * David Herring (https://github.com/abadger1406)
+* Jens Kadenbach (https://github.com/audax)
 * Kolmar Kafran
 * IHLeanne (https://github.com/IHLeanne)
 * Iliya Georgiev (ikgeorgiev@gmail.com)

mayan/apps/installation/classes.py

@@ -7,7 +7,7 @@ import os
 import sh
 
 try:
-    from sh import pip
+    pip = sh.Command('pip')
     PIP = True
 except sh.CommandNotFound:
     PIP = False