Have travis pull in python-all-dbg

Right now it's currently failing to find python3.3-dbg, so hopefully this'll do
the trick. https://travis-ci.org/lmacken/pyrasite/jobs/20793923

.travis.yml

@@ -8,7 +8,7 @@ python:
   - 3.3
 
 install:
-  - sudo apt-get install -qq gdb python${TRAVIS_PYTHON_VERSION}-dbg
+  - sudo apt-get install -qq gdb python-all-dbg
   - python setup.py install
   - if [[ $TRAVIS_PYTHON_VERSION != '2.5' ]]; then pip install coveralls --use-mirrors && export HAS_COVERALLS=1; fi