Improved travis build

Author: syrusakbary

.travis.yml

@@ -14,8 +14,9 @@ cache:
   - $HOME/docs/node_modules
 before_install:
 - |
-  if [ "$TEST_TYPE" != build_website ] && \
-    ! git diff --name-only $TRAVIS_COMMIT_RANGE | grep -qvE '(\.md$)|(^(docs))/'
+  git_diff=$(git diff --name-only $TRAVIS_COMMIT_RANGE)
+  if [ "$?" == 0 ] && [ "$TEST_TYPE" != build_website ] && \
+    ! echo "$git_diff" | grep -qvE '(\.md$)|(^(docs))/'
   then
     echo "Only docs were updated, stopping build process."
     exit