check deflater content type
deflate type check against Rack::Mime::MIME_TYPES

- Rack::Mime::MIME_TYPES
  - now has 604 "file type" => "mime" maps
  - these 604 maps include 535 MIME types
  - all MIME types should deflate or not list in content_type_deflate_expectation
- fix typo
  content_type_deflate_expection -> content_type_deflate_expectation
Adds #bad_request? helper
Adds #unprocessable? helper

* Fixes #252
Adds :old_secret option to Rack::Cookie for graceful key rotation

:old_secret is accept-only, new cookies are signed with the primary
:secret option (or not if :secret is not set)
add .docx and .xlsx mime types.
Ensure correct encoding on chunked responses
Allow the session to be skipped.

This will not send a cookie back nor change the session state.

The :defer option did not send the cookie back but did change the session
state in the backend.

This is useful for assets requests that still go through the rack stack
but do not want to cause any change in the session (for example accidentally expiring flash messages).
Merge pull request #277 from josevalim/skip_session

Allow the session to be skipped.
Merge pull request #260 from alindeman/more_helpers

Adds more Rack::Response helpers
Merge pull request #263 from will/master

Enable graceful secret rotation in Rack::Cookie
Merge pull request #269 from mtfuji/master

.docx and .xlsx
Correct Rack::Directory to escape file names and directories that contain RFC3986 reserved characters
Merge pull request #278 from dim/master

Chunked response, encoding issues
Cleanup the style and minor perf of URLMap

URLMap was a little harder to follow than it need be, so I used my handy
Code Dremel(tm) on it.

I've removed the uses of Hash#merge! since they unnessarily created
extra Hash objects just to update the env.
Merge pull request #280 from evanphx/master

Cleanup URLMap
Add "I'm a Teapot" HTTP Status Code
Fix syntax error on Ruby 1.9
Handle EOFError exception from malformed multipart in MethodOverride middleware
Merge pull request #281 from laserlemon/master

Missing HTTP Status Code