Merge pull request #793 from enthought/dev/use-xenial-linux

Use xenial linux instead of trusty

.travis.yml

@@ -1,5 +1,13 @@
 language: generic
-sudo: false
+
+dist: xenial
+services:
+  - xvfb
+
+addons:
+  apt:
+    packages:
+      - libglu1-mesa
 
 env:
   global:
@@ -26,7 +34,6 @@ cache:
 before_install:
   - mkdir -p "${HOME}/.cache/download"
   - export DISPLAY=:99.0
-  - if [[ ${TRAVIS_OS_NAME} == "linux" ]] ; then sh -e /etc/init.d/xvfb start; fi
   - if [[ ${TRAVIS_OS_NAME} == 'linux' ]]; then ./ci/install-edm-linux.sh; export PATH="${HOME}/edm/bin:${PATH}"; fi
   - if [[ ${TRAVIS_OS_NAME} == 'osx' ]]; then ./ci/install-edm-osx.sh; export PATH="${PATH}:/usr/local/bin"; fi
   - edm install --version ${RUNTIME} -y wheel numpy nose mock Sphinx coverage psutil