update version to 0.2.4

Author: jhgoebbert

setup.py

@@ -5,7 +5,7 @@
 with open(path.join(HERE, 'README.md'), 'r', encoding = 'utf-8') as fh:
     long_description = fh.read()
 
-version='0.2.3'
+version='0.2.4'
 setup(
     name = 'jupyter-xprahtml5-proxy',
     version = version,