- Reintroduce Python 3.2 tests but allow them to fail.

- Consistent indentation in .travis.yml.

.travis.yml

 ---
 language: python
-python: ["2.7", "3.3", "3.4", "3.5"]
+python: ["2.7", "3.2", "3.3", "3.4", "3.5"]
 dist: trusty
 sudo: false
 cache:
   - pip
+matrix:
+  allow_failure:
+    - python: "3.2"
 
 install:
   - pip install tox-travis