Update Rack::Cache URLs
development gems weren't installing with latest
updated format of S3 expiring urls
spec wasn't working without jp2 support but spec slightly redundant
fixed a couple of specs in ruby 1.8.7
Rails doesn't allow mass-assignment by default now
Rack seems to have updated its MIME_TYPES by adding an entry for 'docx'
tests working with latest cucumber - cucumber will be removed soon but keeps it working till then
Cherry-picked 86038fa6e5347f1e87fcd9fb3c6539bb5201c462 and fixed conflicts, so FileDataStore uses YAML instead of marshal
Cherry-picked 78d7ae64ac966794753e1d6b13f5ecfc7eb274a7 : S3 meta now uses simple x-amz-meta headers (but still works with x-amz-meta-extra header)
Conflicts:
	spec/dragonfly/data_storage/s3_data_store_spec.rb
Cherry-picked 8805394fcfd0de9be88f7d680bd0d48d29ff72b7: Mongo meta uses actual meta hash, not marshal dump
Conflicts:
	lib/dragonfly/data_storage/mongo_data_store.rb
Copied Dragonfly::Utils from new_config branch
moved reused symbolize_keys method into Dragonfly::Utils
Cherry-picked 88eaa4bab0473fa8fb70fd5a0957ff3278b7f5d4 : Couch meta is just stored in the normal way as an object, although the old marshal dumped version will still work
Added json_encode and json_decode
use multi_json for JSON encoding
serialize_keys option in Serializer
Use json_encode/json_decode in Models retained_attrs
Job#to_a is JSON compliant
Serializer doesn't replace / with ~ in b64encode - escaping these properly for urls should be the job of the url creator