Update .travis.yml

Fix for #27
Remove pbr in the python 2.6 build since it is not needed and
breaks the build

Author: kevinanderson1

.travis.yml

@@ -7,9 +7,11 @@ python:
 - '3.4'
 - '3.5'
 install:
+- if [[ "$TRAVIS_PYTHON_VERSION" == 2.6* ]]; then travis_retry pip install unittest2; fi
+- if [[ "$TRAVIS_PYTHON_VERSION" == 2.6* ]]; then travis_retry pip uninstall -y pbr; fi
+- if [[ "$TRAVIS_PYTHON_VERSION" == "3.2" ]]; then travis_retry pip install coverage==3.7.1; fi
+- if [[ "$TRAVIS_PYTHON_VERSION" != "3.2" ]]; then travis_retry pip install coverage; fi
 - python setup.py install
-- if [ "$TRAVIS_PYTHON_VERSION" == "3.2" ]; then travis_retry pip install coverage==3.7.1; fi
-- if [ "$TRAVIS_PYTHON_VERSION" != "3.2" ]; then travis_retry pip install coverage; fi
 script:
 - if [[ $TRAVIS_PYTHON_VERSION == '2.6' ]]; then unit2 discover; else python -m unittest discover; fi
 notifications: