[bugfix] I think this needs to call to the class in order to access the
'options' defaults defined there, otherwise it's just accessing the same
'options' (defined on the instance) as the place a few lines down that
 merges the instance options into the default options.

It worked before, because accessing an undefined key in a hash,
returns nil, and the default is also nil, so there was no difference.

However, I want to be able to define a default processing_image_url
that's not nil, so I noticed the problem.
Allowing passing in delayed_paperclip_defaults hash via railties.
Updating readme to discuss updating the default settings ...
config.delayed_paperclip_defaults
Merge pull request #88 from kevinmtrowbridge/delayed_paperclip_defaults

Delayed paperclip defaults