No more need for `sudo` to install `ksh` and `zsh`.

.travis.yml

@@ -1,6 +1,9 @@
 language: c # defaults to ruby
+addons:
+  apt_packages:
+  - zsh
+  - ksh
 install:
-  - sudo apt-get install zsh -y # ksh
   - (mkdir /tmp/urchin && cd /tmp/urchin && curl -s "$(curl -s https://registry.npmjs.com/urchin | grep -Eo '"tarball":\s*"[^"]+"' | tail -n 1 | awk -F\" '{ print $4 }')" -O && tar -x -f urchin*)
   - chmod +x /tmp/urchin/package/urchin
   - '[ -z "$WITHOUT_CURL" ] || sudo apt-get remove curl -y'