JSON support is in all browsers we could conceivably care about; it's
ES5 and has perfect support in IE 8. No need to ship a library as
a core package, and no need to specify dependencies on it.
We could conceivably publish a new version of the `json` package that
is empty, so that apps using packages that still say `use("json")`
also get the code size reduction, but we'll wait until someone requests
that.
This included removing some internal version constraints. It would be
nice if package A could say "use B@2.0.0" (when both have changed), but
when they're both in the release, we need to make a release that has a
B@2.0.0-rc in it, which doesn't match that constraint. Fortunately,
constraints aren't necessary within a release anyway.
Fill in all packages without README.md files with a short
README.md mentioning that this is an internal Meteor package.
Break up the top paragraph of a couple of existing README.md
files to be proper long description.
There is more work to do here, involving line wrapping and the like.
