Always use nightly as travis ci release tag

.travis.yml

@@ -12,8 +12,10 @@ script: npm run build; [ -d dist/public ]
 
 before_deploy:
   # Add tag if missing
-  - if [ -z "$TRAVIS_TAG" ]; then export TRAVIS_TAG=$(date +'%Y%m%d'); git tag -f $TRAVIS_TAG; fi
-  - export RELEASE_TITLE=$TRAVIS_TAG-$(git log --format=%h -1)
+  - if [ -z "$TRAVIS_TAG" ]; then
+      export TRAVIS_TAG=nightly RELEASE_TITLE=$(date +'%Y%m%d')-$(git log --format=%h -1);
+      git tag -f $TRAVIS_TAG;
+    fi
   # Pack for release
   - cp dist/public/{index,login}.html
   - cp INSTALL.md dist