Enable Travis CI

Enable a simple CI via Travis which currently install skopeo and
shellcheck and runs `make validate`.

Fixes: #13
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

.travis.yml

@@ -0,0 +1,9 @@
+sudo: required
+
+before_install:
+        - sudo add-apt-repository ppa:projectatomic/ppa --yes
+        - sudo apt-get update -qq
+        - sudo apt-get install -qq shellcheck skopeo
+
+script:
+        - make validate