req.acceptsCharsets - default to first type if header not set
req.acceptsLanguage - default to first type fi header not set
add debug() for .listen() and .keys=
add DEBUG usage docs. Closes #41
add upload example
docs about yielding control to downstream middleware
docs about middleware composition noop
add blog example
add co-body to blog example
req.is(): make better

closes #105 and #106
change an .is() example

text/* already covers it
add matchesMime() util
remove null return from .is()
change req.is() to return the canonical mime type
readme: fix various typos [no pluralization]

L6: remove redundant "writing".
L99: capitalize "facebook" as "Facebook".

Clean alternative to #109.
refactor ctx.toJSON() to recurse. Closes #108
Merge pull request #110 from silvinci/fix/readme-typo-take2

readme: fix various typos [no pluralization]