Prepare next version

- removed Python 2.7 and 3.4 support from documentation
diff --git a/docs/conf.py b/docs/conf.py
index 3bf42c0..9640868 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -66,9 +66,9 @@
 # built documents.
 #
 # The short X.Y version.
-version = '3.7'
+version = '4.0'
 # The full version, including alpha/beta/rc tags.
-release = '3.7dev'
+release = '4.0dev'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.