Add lang and fix to use bats

Author: tilfin

.travis.yml

@@ -1,6 +1,3 @@
-before_install:
-  - sudo add-apt-repository ppa:duggan/bats --yes
-  - sudo apt-get update -qq
-  - sudo apt-get install -qq bats
-script:
-  - bats test/bats
+language: bash
+install: git clone --depth 1 https://github.com/sstephenson/bats.git
+script: PATH="./bats/bin:$PATH" test/bats