Added file upload server which can be run with server.py or launcher.py

This upload server can be optionally added to the base python web app,
or else run as a child of the launcher, which have been changed to
support this new functionality.

Change-Id: Ia2bc993643a686d7c5e25d92a9dd38441ef2a221
Merge topic 'vtkweb-add-upload-server' into master

4e55f3b3 Added file upload server which can be run with server.py or launcher.py