Re-enable testing on Python 2.7

The problem we encountered previously should be fixed:

https://bitbucket.org/amentajo/lib3to2/commits/25142967e481da45cd69283c8236239cdd57cb5d

Author: myint

.travis.yml

@@ -1,19 +1,28 @@
-sudo: false
-
 language: python
 
 python:
+    - "2.7"
     - "3.2"
     - "3.3"
     - "3.4"
 
+before_install:
+    # This is needed for Python multiprocessing (due to 3to2 dependency).
+    # https://github.com/travis-ci/travis-cookbooks/issues/155
+    - sudo rm -rf /dev/shm
+    - sudo ln -s /run/shm /dev/shm
+
 install:
+    - if [ "$TRAVIS_PYTHON_VERSION" == "2.7" ]; then pip --quiet install 3to2; fi
     - python setup.py --quiet install
 
 script:
-    - python test.py
-    - ./run_doctest.py -v README.rst download_lt.py
-    - ./test.bash
+    - if [ "$TRAVIS_PYTHON_VERSION" != "2.7" ]; then python test.py; fi
+
+    - if [ "$TRAVIS_PYTHON_VERSION" != "2.7" ]; then ./run_doctest.py -v README.rst download_lt.py; fi
+
+    # Prevent Python 2.7 from using the non-3to2 converted code.
+    - cd language_check; ../test.bash
 
     # Smoke test.
     - echo 'This is a sentence.' > foo.txt