shellcheck is now included by default in travis, so no need to install it anymore

.travis.yml

@@ -5,17 +5,9 @@ python:
 # Use container-based infrastructure for quicker build start-up
 sudo: false
 
-addons:
-  apt:
-    sources:
-    - debian-sid    # Grab shellcheck from the Debian repo (o_O)
-
 before_install:
   - git clone https://github.com/piwik/piwik-package.git tmp/piwik-package
   - composer install
-  - "sudo apt-get install cabal-install"
-  - "cabal update"
-  - "cabal install shellcheck"
 
 script:
  - 'shellcheck *.sh'