Add support for jobs with spaces in the name.
Refactor job validation, add job-name validation.

Pull out the common code for validating a job form to a single
method, and make sure that incoming jobs don't have quotes or
backslashes in their names (which would mess with the wrapper
scripts that run the job).
Update the worker node type and AMI
Update to version 8.

This releases support for jobs with spaces in their names, bigger
instance types, and general code cleanup.
Merge branch 'job_names_with_spaces'