Rename the test schema file.
Fix the documentation task in the Rakefile.
Switch to Peck in test helper.
Don't use #class_method for attachment options.

For some reason defining the global attachment options as a class_variable mis-
behaves on Rails 4.1. Because the options are copied over to subclasses when
defining them anyway we use a regular class accessor.
Add support for instrumentation.

Adds an instrument for attachement_san.process_variant and .process_original.
This allows you to catch these events and log them in your Rails app if wanted.
Don't assume test/unit in the test helper.
Don't memoize filename methods.

It's not a slow operation and can only make problems in the future.
Only try upload when there is an original file.

When someone tries to create assets without an upload we don't want it to
break.
Fix tests for difference with Peck.

Peck has some assertions which work a little bit different from test/spec so we
need to make some changes here and there.
Set polymorphic source for all attachments.

In the tests we need to set the polymorphic source for all attachments or Rails
will try to find the foreign key.
Remove deprecated :order from associations.
We now use a full path in test models.
Add spec for attachment without upload.
Rename README and add a note about testing.
Add a Gemfile for easy developer setup.
Generate Gemfile.lock.