Add pandoc to TravisCI config

.travis.yml

@@ -1,18 +1,19 b''
 # http://travis-ci.org/#!/ipython/ipython
 language: python
 python:
     - 2.6
     - 2.7
     - 3.2
     - 3.3
 before_install:
     - easy_install -q pyzmq
     - easy_install pygments
     - easy_install jinja2
     - easy_install markdown
     - easy_install sphinx
+    - sudo apt-get install pandoc
 install:
     - python setup.py install -q 
 script:
     - if [[ $TRAVIS_PYTHON_VERSION == '2.'* ]]; then iptest -w /tmp; fi
     - if [[ $TRAVIS_PYTHON_VERSION == '3.'* ]]; then iptest3 -w /tmp; fi