don't bother installing bats, just clone it

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index e56169a..deeb1bc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,6 @@
 language: bash
-before_install:
-  - ./script/install-bats.sh
+install:
+  - git clone --depth 1 https://github.com/sstephenson/bats
   - git clone --depth 1 https://github.com/ztombol/bats-support ../bats-support
-before_script:
-  - export PATH="${HOME}/.local/bin:${PATH}"
 script:
-  - bats test
+  - ./bats/bin/bats test