Merge pull request #125 from dcrosta/drop-mongo-32

Drop support for MongoDB 3.2, its end of life was Sept 2018

Author: dcrosta

tox.ini

@@ -2,11 +2,10 @@
 
 ; keep the pymongo list in sync with what's in .travis.yaml
 envlist=
-    pymongo{33,34,35,36,37,38}-mongo{32,34,36,40,41}-flask{0_11,0_12,10}, style
+    pymongo{33,34,35,36,37,38}-mongo{34,36,40,41}-flask{0_11,0_12,10}, style
 
 [testenv]
 docker =
-    mongo32: mongo:3.2
     mongo34: mongo:3.4
     mongo36: mongo:3.6
     mongo40: mongo:4.0