* In -dev mode, `ioutil.TempDir` is used for the alloc and state
directories.
* `TempDir` uses `$TMPDIR`, which os OS X contains a per user
directory which is under `/var/folder`.
* `/var` is actually a symlink to `/private/var`
* Docker For Mac validates the directories that are passed to bind and on
OS X. That whitelist contains `/private`, but not `/var`. It does not
expand the path, and so any paths in `$TMPDIR` fail the whitelist check.

And thusly, by expanding the alloc/state directories the value passed
for binding does contain `/private` and Docker For Mac is happy.

The syslog logging system depends on the ability for a unix socket to be
accessed by the docker daemon in the $TMPDIR of the host. This doesn't
work on Docker For Mac because the docker daemon is running inside a VM,
and while /tmp is accessible, the filesystem used to share them doesn't
support unix socket files, and thus it doesn't work.