Clean up after r39484 and r39486.

Clean up after r39484 and r39486.

In particular, this adds CHANGELOG entries for packages that have been
modified and fixes pub's barback dependency so it doesn't declare
compatibility on an uncut release.

This releases args, barback, http_parser, and shelf.

R=rnystrom@google.com

Committed: https://code.google.com/p/dart/source/detail?r=39563

[nweiz, 2014-08-26 18:31:28]

nweiz@google.com changed reviewers:
+ rnystrom@google.com

[nweiz, 2014-08-26 18:31:28]

Lasse: when updating packages (especially those you don't work on regularly),
it's important to follow the versioning policy:
https://docs.google.com/a/google.com/document/d/1kPhEF8rL53S45SpzboyddKW61EUn....
In particular, when you change a package to a non-dev version, upload that
version to the repo packages match those on pub.dartlang.org.

Also, the change you made to pub's barback constraint is dangerous and could
cause a lot of user pain if it made it into the wild, as I explained this in
https://codereview.chromium.org/497703002/.

[Bob Nystrom, 2014-08-26 19:43:25]

lgtm

[nweiz, 2014-08-26 19:49:55]

Committed patchset #1 manually as 39563 (presubmit successful).