[travis] Remove py3.4 build

Removing Python 3.4 since support for it
is discontinued by March 2019.

Author: mpsonntag

.travis.yml

@@ -8,8 +8,6 @@ matrix:
     - os: linux
       python: "2.7"
       env: COVERALLS=1
-    - os: linux
-      python: "3.4"
     - os: linux
       python: "3.5"
     - os: linux