support for storing & retrieving custom metadata

This commit adds support and a test for storing and retrieving
custom metadata for S3 objects, as documented at:

    http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPUT.html
added section on installing test dependencies
added ruby version and gemset configuration
added configuration for running tests
load existing s3 objects when server is started
merged custom attributes branch from https://github.com/hblanks/fake-s3:master
objects now have a storage class
added admin control commands
added several states to an object
support restore call changing the state of the object
tests pass
added documentation about the development REST api
uncommented out a long running test
Merge pull request #1 from jwliechty/f-add_meta_commands

F add meta commands