Merge branch 'test_pr_for_danger'

Configure and enable Danger for automatical code review.

See: http://danger.systems

Fix #536

Author: php-coder

.travis.yml

@@ -16,6 +16,9 @@ before_script:
       npm install -g bootlint;
       pip install --user html5validator;
       pip install --user robotframework-lint;
+      if [ "$TRAVIS_PULL_REQUEST" != 'false' ]; then
+        gem install danger nokogiri --no-ri --no-rdoc;
+      fi;
     fi
 
 script: