Added geckodriver to travis.yml

.travis.yml

@@ -4,6 +4,11 @@ os:
   - linux
 python:
   - 3.6
+before_install:
+  - wget https://github.com/mozilla/geckodriver/releases/download/v0.24.0/geckodriver-v0.24.0-linux64.tar.gz
+  - mkdir geckodriver
+  - tar -xzf geckodriver-v0.24.0-linux64.tar.gz -C geckodriver
+  - export PATH=$PATH:$PWD/geckodriver
 install:
   - pip install -r requirements.txt
   - pip install flake8