add request.hostname(getter), fixed #224

make request.host and request.hostname work as node url lib
http://nodejs.org/api/url.html#url_url
this commit will change older request.host(getter)
Debug name koa:context -> koa:request
Merge pull request #226 from slaskis/patch-1

debug name koa:context -> koa:request
Merge pull request #225 from dead-horse/issue224-host-confused

add request.hostname(getter), fixed #224
Revert "add response.charset accessor and ctx.charset alias"

This reverts commit 94413b1bd4f20b8c4b183c84166fdfb71087aff6.
Release 0.5.1
Let errors provide their own status.

When calling `ctx.throw`, you're allowed to provide an error object and a
status code. The status code is later set as the `status` property of the error
object. If no status code is provided, it defaults to 500. However, this
happens even if the error object already had a `status` property.

This commit allows an error's pre-existing `status` property to be used in
conjunction with `ctx.throw`.

If the status code is below 500, the error message will be exposed to the user
in the HTTP response. It would be nice to have some Error subclasses that
always have the same status code, because then we could just write
`ctx.throw(new WhateverError())`, and define which 4xx error code we want in
the definition of `WhateverError` itself. If, for example, an
`AuthenticationError` is always meant to go along with a 401, then it would be
nice to just have that knowledge in the class definition.
Merge pull request #232 from altruism/master

Let errors provide their own status.
fix some typos in koa-vs-express docs
Update context.md

ctx.type is delegated to this.response.
Merge pull request #233 from alsotang/patch-1

Update context.md
add subreddit to Community list
Merge pull request #235 from gdi2290/patch-1

add subreddit to Community list
Fix broken reddit community link

Add required protocol to link
Merge pull request #236 from phillipalexander/patch-1

Fix broken reddit community link
Update koa-vs-express.md
fix some tests that never worked
add app.toJSON()
fix inspection of app. Closes #108
refactor: use statuses