Use JWM window manager to improve Firefox UI interaction

Without a window manager, much of the Firefox UI is not displayed within Xvfb, such as popup notifications, dropdowns, menus, etc. This light-weight window manager has tested successfully.

.travis.yml

@@ -14,18 +14,30 @@ matrix:
     - python: 2.7
       env: FIREFOX=nightly
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-nightly
     - python: 2.7
       env: FIREFOX=dev
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-dev
     - python: 2.7
       env: FIREFOX=beta
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-beta
     - python: 2.7
       env: FIREFOX=release
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest
     - python: 3.6
       env: TOXENV=flake8
@@ -34,41 +46,51 @@ matrix:
     - python: 3.6
       env: FIREFOX=nightly
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-nightly
     - python: 3.6
       env: FIREFOX=dev
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-dev
     - python: 3.6
       env: FIREFOX=beta
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest-beta
     - python: 3.6
       env: FIREFOX=release
       addons:
+        apt:
+          packages:
+            - jwm
         firefox: latest
   exclude:
     - python: 2.7
     - python: 3.6
-
 before_install:
   - wget -O /tmp/geckodriver.tar.gz https://github.com/mozilla/geckodriver/releases/download/v0.13.0/geckodriver-v0.13.0-linux64.tar.gz
   - mkdir $HOME/geckodriver && tar xvf /tmp/geckodriver.tar.gz -C $HOME/geckodriver
   - export PATH=$HOME/geckodriver:$PATH
   - firefox --version
   - geckodriver --version
-
 install:
   pip install tox-travis
-
 notifications:
   webhooks:
     urls:
       - "https://silne30-foxpuppet.getbadges.io/api/app/webhook/b71ddba7-6feb-412c-8728-3efef552d02b"
     on_start: "change"
-
 before_script:
   - sh -e /etc/init.d/xvfb start
-
+  - sleep 10
+  - jwm &
+  - sleep 10
 script:
   - tox