Remove deprecated packages from pkg directory.

Remove deprecated packages from pkg directory.

The packages are deprecated, and will probably never be changed again. There is no need for them to be in the repository.
If we ever need to make a change, we can get the code from pub instead.

BUG= http://dartbug.com/16528
R=sethladd@google.com

Committed: https://code.google.com/p/dart/source/detail?r=32488

[sethladd, 2014-02-05 14:39:05]

lgtm

[kevmoo, 2014-02-05 17:42:57]

I'll do a separate push to create README files for these.

We need to make sure pub.dartlang.org is updated and helpful for deprecations.

[Lasse Reichstein Nielsen, 2014-02-06 08:54:36]

On 2014/02/05 17:42:57, kevmoo wrote:
> I'll do a separate push to create README files for these.
> 
> We need to make sure http://pub.dartlang.org is updated and helpful for
deprecations.

Thanks. I've added you as uploader on sequence_zip and unmodifiable_collection
(collection_helpers already has a README.md).

[Lasse Reichstein Nielsen, 2014-02-10 10:24:05]

Committed patchset #1 manually as r32488 (presubmit successful).