Parts now have PrintJobs!

* Photos, measurements, state tracking, shipping info all pushed down
* New "reject" state so we can track rejected jobs
* (Separately) copied part photos over to print_job on S3.
* Parts admin and part/print_job workflow are as before. Changes coming.
Use size vs count in project part avail check
Update Rails to 4.0.6
Work around(?) Postgresql/AREL issue

Nested contexts cause prepared statement errors.

See https://github.com/rails/rails/issues/10995

This attempts to work around it but I don't have pgsql running locally so I get
to push it live to find out if it works. :P
Fix image tag for messing photo for asset pipeline
User no longer needs a "parts" accessor.
Move part file storage to ModelFile class

Managed by (a progressively more frustrating to use) Paperclip.

Temporary rake task tmp:part_models_to_model_files should handle the migrate.

Part#download_url helper method manages the difference between migrated and
unmigrated Parts, for now.
Move part preview image to ModelFile#render

Managed by Paperclip. Helper function hides unmigrated junk

Also: temp rake task for migrating
Remove old migration rake tasks
Purge model/preview url data from part model

It's now down in a ModelFile model
Fix Paperclip whining about photo validator
DB seeds for Ben Franklin
Drop Franklin parts db seeding
Make sure STL download URL doesn't include tstamp
Attempt to use correct CORS domain for STL preview
Revert to s3.amazonaws.com/bukkit/ -style urls
Part names as X/Y/Z vs # id. Add marking instruct.
Send emails around part verification??

SMTP settings go in ENV. See the initializer.
Fix up SMTP config initializing
Gross workaround of pgsql prep stmt bug for part assignment