Replaced File I/O usage w/ new library

[mjohnsonengr]

Added dependency on GaeVFS: https://code.google.com/p/gaevfs/

Google App Engine doesn't support normal File I/O operations; GaeVFS translates a virtual file system into app engine datastore.

There are other places where a similar change could be made in code; This pull request can initiate those changes. This increases appengine-awt's compatibility with appengine.