add sudo to apt command.

Author: rouilj

.travis.yml

@@ -58,7 +58,7 @@ before_install:
   - if [[ $TRAVIS_PYTHON_VERSION == "2."* ]]; then pip install sphinx==1.8.5; fi
   - if [[ $TRAVIS_PYTHON_VERSION == '3.'* ]] ; then pip install sphinx; fi
   - if [[ $TRAVIS_PYTHON_VERSION == "nightly" ]]; then pip install sphinx; fi
-  - apt-get update && apt-get upgrade libxapian-dev libxapian
+  - sudo apt-get update && sudo apt-get upgrade libxapian-dev libxapian
   - XAPIAN_VER=$(dpkg -l libxapian-dev | tail -n 1 | awk '{print $3}' | cut -d '-' -f 1); echo $XAPIAN_VER
   - cd /tmp
   - curl -s -O https://oligarchy.co.uk/xapian/$XAPIAN_VER/xapian-bindings-$XAPIAN_VER.tar.xz