Problem: BigchainDB does not support newer MongoDB (#2298)

* Problem: BigchainDB does not support newer MongoDB

Solution: Update driver to the last version, that is compatible with all
versions of MongoDB

* Update to MongoDB 3.6

docker-compose.yml

@@ -4,7 +4,7 @@ services:
   # Build: docker-compose build -d bigchaindb
   # Run: docker-compose run -d bdb
   mongodb:
-    image: mongo:3.4.13
+    image: mongo:3.6
     ports:
       - "27017"
     command: mongod

k8s/mongodb/container/Dockerfile

@@ -1,4 +1,4 @@
-FROM mongo:3.4.13
+FROM mongo:3.6
 LABEL maintainer "dev@bigchaindb.com"
 WORKDIR /
 RUN apt-get update \

setup.py

@@ -73,7 +73,7 @@ benchmarks_require = [
 install_requires = [
     # TODO Consider not installing the db drivers, or putting them in extras.
     'rethinkdb~=2.3',  # i.e. a version between 2.3 and 3.0
-    'pymongo~=3.4',
+    'pymongo~=3.6',
     'pysha3~=1.0.2',
     'cryptoconditions~=0.6.0.dev',
     'python-rapidjson==0.0.11',