fix default urs for split processing

When doing split processing, we have some styles already available, even
though the background processing is still ongoing. We must return those
instead of the missing picture url
Merge pull request #75 from tdgs/fix_split_processing

fix default urs for split processing
Cleaned up Rake and Testing files

Dropped support for Rails 3
Dropped support for Ruby 1.8
Added support for Rails 4
Constrained paperclip to 3.3..4 for now
Merge pull request #77 from ScotterC/clean-up-appraisal

Cleaned up Rake and Testing files
Testing Support for paperclip 4

Validation now required
Merge pull request #78 from ScotterC/paperclip-4

Testing Support for paperclip 4
Merges in #62

Fix for when attachment is set on a parent class (eg ActiveRecords STI)
The only_process was nil which wasn't being checked against [] very well
only_process now defaults to []
Merge pull request #79 from ScotterC/merging-in-62

Merges in #62
bump version
Fixed bug on models with multiple attachments, where once _first_ attachment is processed, _all_ are mistakenly marked as processed
Multiple-attachment-bugfix tests converted to RSpec