Automatic test scenes job improvements

[x] Add a lock system to ensure a job can start if another job is running
[x] Place the build report in the web server
[ ] Add the commit link in the build report in the travis deploy script
[ ] Don't run tests if no build was deployed since last test
[x] Use a domain name
[ ] Fix test scenes execution order (should be alphabetically, seems random at the moment)
[ ] Make execution log files of already rendered scenes accessible during execution
[x] Investigate test scenes that seem to render fine but are marked as failed
[ ] Don't run tests in the build directory

appleseedhq / appleseed