Make the jupyterlab python tests local

MANIFEST.in

@@ -1,3 +1,4 @@
 recursive-include jupyterlab/build *
 include jupyterlab/lab.html
 include package.json
+prune jupyterlab/tests

scripts/travis_script.sh

@@ -18,7 +18,7 @@ npm test
 npm run test:coverage
 
 # run the python tests
-nosetests -v jupyterlab
+cd jupyterlab && nosetests
 
 npm run build:examples
 npm run docs