Allow some settings to be from a file [not checked in after initial push]
* Creates a global Constant, EnvSettings
* Creates a QA environment database
* Adds code to allow global settings (used to assign values to EnvSettings)
CYB-121 Updates to existing student records should not cause an exception, uniqueness violation
Make submissions editable -- resubmitting will now change what appears in the gallery
 * shows only the last submission
 * Attachment model / attachments table added
 * app/services/canvas/attachments_processor.rb added
 * also don't do many actions if there is no change
Merge pull request #55 from coyote/fix_student_import

CYB-121 Fix student import
Merge pull request #51 from coyote/manage_env_confs

Allow some settings to be from a file [not checked in after initial push]
Merge pull request #59 from coyote/edit_submissions

Make submissions editable -- resubmitting will now change what appears i...
CYB-122 Sync activity updating
* fixed issues with builders (no such field as 'uid' and was missing fields as well)
* student scores are recomputed and cached on call to Activity.update_scores!
  * This is called by the EngagementIndexScoringProcessor, which in turn is called by the cron updater and the thor (hand) updater