Default erb content type to text/plain
Fewer magic test numbers
@digest is no longer used
Don't need to "expire cache"
Make logger global configuration
Move context class to global config
Make digest_class global config
Make version global
Copy over root in configuration
Tidy whitespace
Skip context require
Ensure accept encoding content type is set
Assert content encoded etag is different than unecoded etag

Note: Content codings are a property of the representation data, so a strong
entity-tag for a content-encoded representation has to be distinct from the
entity tag of an unencoded representation to prevent potential conflicts
during cache updates and range requests. In contrast, transfer codings apply
only during message transfer and do not result in distinct entity-tags.