#209 try the RTD solution with Mock objects

See https://docs.readthedocs.io/en/stable/faq.html#i-get-import-errors-on-libraries-that-depend-on-c-modules
Tested locally ok.

docs/source/conf.py

@@ -19,6 +19,18 @@
 #
 import os
 import sys
+from unittest.mock import MagicMock
+
+
+class Mock(MagicMock):
+    @classmethod
+    def __getattr__(cls, name):
+        return MagicMock()
+
+
+MOCK_MODULES = ['osgeo', 'psycopg2.sql', 'elasticsearch']
+sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
+
 sys.path.insert(0, os.path.abspath('../..'))