Fix package

The package.json file and the .tgz should be included in the
distribution.

The package.json is needed by the setup.py for the js version, which was
not the case before. And the .tgz file is needed for the JupyterLab
extension installation.

Signed-off-by: martinRenou <[email protected]>

Author: martinRenou

MANIFEST.in

@@ -1,2 +1,4 @@
 recursive-include ipyleaflet/static *.*
 include jupyter-leaflet.json
+include js/*tgz
+include js/package.json

setup.py

@@ -55,7 +55,7 @@ def run(self):
 
 
 def get_data_files():
-    with open(os.path.join('js', 'package.json')) as f:
+    with open(os.path.join(node_root, 'package.json')) as f:
         package_json = json.load(f)
     tgz = '%s-%s.tgz' % (package_json['name'], package_json['version'])