Added upload date to project

Added the 'uploaddate' field to project, which is just a timestamp of
when the project was uploaded to the site. Also set default order by in
the project model to be uploaddate desc, meaning newest projects will be
displayed first.

Added:
* migrations\009_project_upload_date.php ~ migration for adding
'uploaddate' timestamp field to project table

Changes:
* config/migration.php ~ bumped migration version
* controllers/admin/project.php ~ added code to inject upload date
timestamp into new projects
* models/project_m.php ~ set default order by to 'uploaddate DESC' which
grabs the newest projects first