Drop support for Python 3.4 because it is now EOL

Remove support for Python 3.4 because that release has reached its end of life.
* https://devguide.python.org/devcycle/#end-of-life-branches

Author: cclauss

.travis.yml

@@ -2,12 +2,10 @@ language: python
 matrix:
   include:
     - python: 2.7
-    - python: 3.4
     - python: 3.5
     - python: 3.6
     - python: 3.7
       dist: xenial
-      sudo: true
 cache: pip
 before_install:
 - '[ "${TRAVIS_PULL_REQUEST}" = "false" ] && openssl aes-256-cbc -K $encrypted_cebf25e6c525_key