Travis: Implement yaml checking for Snappy

This patch enables Travis CI to check the snapcraft.yaml files for any
potential problems.  Yamllint installation is implemented in the script
which, might be sane to be moved to .travis.yml instead.

Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

.travis.yml

@@ -44,6 +44,7 @@ before_install:
 
 script:
     - scripts/travis-check-translations.sh
+    - scripts/travis-check-snappy-yamllint.sh
     # don't build directly, create a tarball first and try building from that
     - ./bootstrap && ./configure && make dist && make distcheck
 

scripts/travis-check-snappy-yamllint.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env sh
+# This script checks the snapcraft configuration YAML files 
+# according to the rules at /snappy/.yamllint
+set -o errexit -o nounset
+
+pip install --user yamllint
+yamllint --version
+
+for snapcraft_config in snappy/poedit*/snap/snapcraft.yaml ; do
+    yamllint --config-file snappy/.yamllint "${snapcraft_config}"
+done