Fix broken build on readthedocs, third attempt

This actually breaks the < 1.3 builds (as sadly there is no way to
specify the requirements file per version, it is a global setting).
Since we do not actually need to build more docs for 1.2 or less, this
is not too much of a problem.

Author: stefano-maggiolo

docs/conf.py

@@ -13,25 +13,6 @@
 
 import sys, os
 
-
-
-# To avoid builds failing because of missing C libraries, see:
-# http://read-the-docs.readthedocs.org/en/latest/faq.html
-#   #i-get-import-errors-on-libraries-that-depend-on-c-modules
-try:
-    from unittest.mock import MagicMock
-except ImportError:
-    from mock import Mock as MagicMock
-
-class Mock(MagicMock):
-    @classmethod
-    def __getattr__(cls, name):
-            return Mock()
-
-MOCK_MODULES = ['pycups']
-sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
-
-
 # If extensions (or modules to document with autodoc) are in another directory,
 # add these directories to sys.path here. If the directory is relative to the
 # documentation root, use os.path.abspath to make it absolute, like shown here.