Make sure we get the geckodriver on travis

Author: benmurden

.travis.yml

@@ -10,6 +10,12 @@ sudo: false
 addons:
   firefox: latest
 
+before_install:
+    - wget https://github.com/mozilla/geckodriver/releases/download/v0.21.0/geckodriver-v0.21.0-linux64.tar.gz
+    - mkdir geckodriver
+    - tar -xzf geckodriver-v0.21.0-linux64.tar.gz -C geckodriver
+    - export PATH=$PATH:$PWD/geckodriver
+
 env:
     matrix:
         - DJANGO=1.8