Use qmk docker image for travis CI builds

util/travis_test.sh

@@ -0,0 +1,29 @@
+#!/bin/bash
+
+TRAVIS_COMMIT_MESSAGE="${TRAVIS_COMMIT_MESSAGE:-none}"
+TRAVIS_COMMIT_RANGE="${TRAVIS_COMMIT_RANGE:-HEAD~1..HEAD}"
+
+# test force push
+#TRAVIS_COMMIT_RANGE="c287f1bfc5c8...81f62atc4c1d"
+
+NUM_IMPACTING_CHANGES=$(git diff --name-only -n 1 ${TRAVIS_COMMIT_RANGE} | grep -Ecv '^(docs/)')
+BRANCH=$(git rev-parse --abbrev-ref HEAD)
+
+if [[ "$TRAVIS_COMMIT_MESSAGE" == *"[skip test]"* ]]; then
+    echo "Skipping due to commit message"
+    exit 0
+fi
+
+if [ "$BRANCH" != "master" ] && [ "$NUM_IMPACTING_CHANGES" == "0" ]; then
+    echo "Skipping due to changes not impacting tests"
+    exit 0
+fi
+
+# if docker is installed - call make within the qmk docker image
+if command -v docker >/dev/null; then
+  function make() {
+    docker run --rm -e MAKEFLAGS="$MAKEFLAGS" -w /qmk_firmware/ -v "$PWD":/qmk_firmware qmkfm/qmk_firmware make "$@"
+  }
+fi
+
+make test:all