Remove the http package from the repo.

pkg/http/CHANGELOG.md

-## 0.11.1+2
-
-* Widen the version constraint on `unittest`.
-
-## 0.11.1+1
-
-* Widen the version constraint for `stack_trace`.
-
-## 0.11.1
-
-* Expose the `IOClient` class which wraps a `dart:io` `HttpClient`.
-
-## 0.11.0+1
-
-* Fix a bug in handling errors in decoding XMLHttpRequest responses for
-  `BrowserClient`.
-
-## 0.11.0
-
-* The package no longer depends on `dart:io`. The `BrowserClient` class in
-  `package:http/browser_client.dart` can now be used to make requests on the
-  browser.
-
-* Change `MultipartFile.contentType` from `dart:io`'s `ContentType` type to
-  `http_parser`'s `MediaType` type.
-
-* Exceptions are now of type `ClientException` rather than `dart:io`'s
-  `HttpException`.
-
-## 0.10.0
-
-* Make `BaseRequest.contentLength` and `BaseResponse.contentLength` use `null`
-  to indicate an unknown content length rather than -1.
-
-* The `contentLength` parameter to `new BaseResponse` is now named rather than
-  positional.
-
-* Make request headers case-insensitive.
-
-* Make `MultipartRequest` more closely adhere to browsers' encoding conventions.