Fixed a bug where the logger wasn't configured properly.
Changed chunk_copy so that it creates the checksum and returns it.
Changed WSGI startup script to optionally use sessions.

Fixed
=====

* This startup script now works with modwsgi running in *daemon* mode.
  It seems that using the sessions database was messing this up. So
  sessions are now disabled by default.

Changed
=======

* Sessions are now disabled by default. The is controlled by the environment
  variable, WMT_ENABLE_SESSIONS.

* Using sessions
Removed custom 404 message.
Changed upload_large_file to stream file as a multipart-upload.

Changed
=======

* upload_large_file now uses the MultipartEncoder class from
  requests_toolbelt to stream a file to a server.
Changed to remove references to session data, like username.
Changed to not pass session data to templates.
Changed run methods to refer to model runs by uuid rather than id.
Merge branch 'master' of https://github.com/csdms/wmt