Upgrade travis config

Author: gnestor

.travis.yml

@@ -25,8 +25,10 @@ install:
 script:
 - yarn
 - yarn run build
+- jupyter labextension link packages/fasta-extension --no-build
 - jupyter labextension link packages/geojson-extension --no-build
-- jupyter labextension link packages/plotly-extension --no-build
 - jupyter labextension link packages/katex-extension --no-build
+- jupyter labextension link packages/plotly-extension --no-build
+- jupyter labextension link packages/vega2-extension --no-build
 - jupyter lab build 
 - python -m jupyterlab.selenium_check