[travis] Add missing dependencies.

.travis.yml

@@ -2,7 +2,7 @@ after_success:
 - coveralls -e _travis/install -e tests
 - git config --global user.name "Travis CI"
 - git config --global user.email "thomas.moulard+travis@gmail.com"
-- git remote set-url origin https://thomas-moulard:${GH_TOKEN}@github.com/stack-of-tasks/dynamic-graph.git
+- git remote set-url origin https://thomas-moulard:${GH_TOKEN}@github.com/stack-of-tasks/dynamic-graph-python.git
 - git fetch origin gh-pages:gh-pages
 - cd _travis/build/doc && ../../../cmake/github/update-doxygen-doc.sh
 branches:
@@ -17,7 +17,7 @@ matrix:
 before_install:
 - git submodule update --init --recursive
 - sudo apt-get update -qq
-- sudo apt-get install -qq doxygen doxygen-latex libboost-all-dev libeigen3-dev liblapack-dev libblas-dev gfortran python-dev
+- sudo apt-get install -qq doxygen doxygen-latex libboost-all-dev libeigen3-dev liblapack-dev libblas-dev gfortran python-dev python-sphinx
 - sudo pip install cpp-coveralls --use-mirrors
 language: cpp
 notifications: