Travis: Add Python 3.7 on Linux

Closes #2427

.travis.yml

@@ -81,6 +81,29 @@ matrix:
       - sudo apt-get update -qq
       - sudo locale-gen fr_FR.UTF-8 tr_TR.UTF-8
 
+  - os: linux
+    python: 3.7
+    env: TOX_ENV=py37
+    distro: xenial
+    before_install:
+      - sudo add-apt-repository ppa:deadsnakes/ppa -y
+      - sudo apt-get update
+      - sudo apt-get install python3.7
+      - python -m pip install virtualenv --user
+      - virtualenv venv
+      - source venv/bin/activate
+      - python -m pip install --upgrade pip wheel
+      - pip --version
+      - python -m pip install --upgrade pip wheel
+      - python -m pip install -r requirements/test.pip
+      - python -m pip install nose nose-cov coveralls pygments==2.1.3
+      - sudo apt-get update -qq
+      - sudo locale-gen fr_FR.UTF-8 tr_TR.UTF-8
+    install:
+      - python -m pip install .
+    script:
+      - nosetests -sv --with-coverage --cover-package=pelican pelican
+
 
   - os: windows
     env: TOX_ENV=py27-win