simplify travis

.travis.yml

@@ -20,7 +20,7 @@ before_install:
   - rm -rf ~/.gnupg
 
 before_script:
-  - sudo rm -rf /etc/mysql/
+  - sudo rm -rf /etc/mysql
   - sudo bash -c 'echo example.com > /etc/hostname'
   - sudo apt-get -qq purge mysql* graphviz* redis*
   - sudo apt-get -qq autoremove --purge