More Travis-CI corrections.

Signed-off-by: Eric F Crist <ecrist@secure-computing.net>

.travis.yml

@@ -1,15 +1,11 @@
 language: bash
 
-sudo: false
+os:
+     - linux
 
-addons:
-  apt:
-    sources:
-    - debian-stretch
-    packages:
-    - shellcheck
+sudo: false
 env:
- - PATH=/usr/bin:/bin:./
+     - PATH=/usr/bin:/bin:./:/usr/local/bin
 script:
  - which shellcheck
  - shellcheck -V