Update pip before starting the Travis tests

Signed-off-by: Jeremy Cline <jeremy@jcline.org>

.travis.yml

@@ -8,7 +8,8 @@ python:
 
 # Twisted dropped Python 2.6 support, so install a compatible version on 2.6
 install:
- - if [[ $TRAVIS_PYTHON_VERSION == 2.6 ]]; then pip install Twisted==12.2; fi
+ - pip install --upgrade pip setuptools
+ - if [[ $TRAVIS_PYTHON_VERSION == 2.6 ]]; then pip install Twisted==12.2 linecache2; fi
  - pip install -e .[commands,consumers]
  - pip install nose
 script: python setup.py nosetests