CANVAS-207 modify deployment process for zero-downtime

blank out default migrate task

remove empty QTIMigration folder

undo db:migrate stub-out

Turns out we actually do need to call it.

remove references to hotfix

No more hotfixes - all deploys are now zero-downtime

remove --quiet flags

move copy_config to before_create_symlink

add a task to call db:migrate:predeploy

add a ping task to kickstart the passenger restart

don't show the maintenance page

reorder load_notifications and migrate

add canvas_url to testing staging and production files

fix typo in staging.rb

use CANVASDIR to point copy_config at the right place

whitespace
Merge pull request #95 from grahamb/canvas-207-deploy

Implement CANVAS-207 - zero-downtime deploys