Modified conf.py to use default theme for rtd

doc/source/conf.py

@@ -161,10 +161,13 @@ todo_include_todos = False
 
 # The theme to use for HTML and HTML Help pages.  See the documentation for
 # a list of builtin themes.
-import sphinx_rtd_theme
-
-html_theme = "sphinx_rtd_theme"
 
+on_rtd = os.environ.get('READTHEDOCS') == 'True'
+if on_rtd:
+    html_theme = 'default'
+else:
+    import sphinx_rtd_theme
+    html_theme = 'sphinx_rtd_theme'
     html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 #html_theme = 'alabaster'