make SignableRequest#form_encoded? public
timestamp and nonce may be omitted with PLAINTEXT
drop the 'access token' terminology in favor of simply 'token'. access token is neither part of the final oauth spec, nor in the grandfathered-in naming of parameters, so it should not be included.
test setting of rack env variables
oauth request body hash initial. code, documentation, and even a couple tests (the ones from the example)
check if the oauth body hash actually makes any sense to receive
turn off body hash for existing tests which don't expect it
test SignableRequest's body hash functionality
add tests for SignedRequest and config methods relating to body hash
test signed request when it has a body hash with PLAINTEXT
compare media type case-insensitively
Merge branches 'media_type', 'plaintext_nonce_timestamp', 'token_not_access_token' and 'body_hash' into HEAD