Update travis config to exclude old Python versions

Author: martialblog

.gitignore

@@ -33,6 +33,7 @@ var/
 *.egg-info/
 .installed.cfg
 *.egg
+.venv/
 
 # PyInstaller
 #  Usually these files are written by a python script from a template

.travis.yml

@@ -1,13 +1,12 @@
 language: python
 python:
-  - "3.3"
-  - "3.4"
   - "3.5"
   - "3.6"
+  - "3.7"
 install:
   - pip install coveralls
   - pip install coverage
-  - pip install pylint==1.9.3
+  - pip install pylint==2.3.1
 script:
   - pylint cheat
   - python -m unittest discover