Clarify User and MemorySwap are platform specific

[coolljt0725]

based on the runtime spec, the user are platform-specific and MemorySwap are for Linux based systems.

Fixed #329

Actually, I'd like to remove Memory MemorySwap CpuShares

[wking]

On Sat, Oct 08, 2016 at 02:33:13AM -0700, Lei Jitang wrote:

based on the runtime spec, the user are platform-specific and
MemorySwap are for Linux based systems.

Solaris also supports the user fields 1. Both Solaris 2 and
Windows 3 have similar-ish memory settings, but they aren't quite
MemorySwap.

Actually, I'd like to remove Memory MemorySwap CpuShares

I'd rather use the runtime-spec config.json [4,5,6]. It saves us from
having to copy over settings from runtime-spec, and leaves the “what
settings do I think are safe?” descision up to the image-consumer (who
can use a stock sanitization script if they want).

[coolljt0725]

@wking

Solaris also supports the user fields [1]. Both Solaris [2] and
Windows [3] have similar-ish memory settings, but they aren't quite
MemorySwap.

Solaris does have user, I didn't say that Solaris doesn't user field. but we doesn't clarify that the image spec is support for Solaris at the moment :)
Windows and Solaris do have memory limit, but it's not MemorySwap

[wking]

On Tue, Oct 11, 2016 at 01:41:09AM -0700, Lei Jitang wrote:

Solaris also supports the user fields [1]. Both Solaris [2] and
Windows [3] have similar-ish memory settings, but they aren't
quite MemorySwap.

Solaris does have user, I didn't say that Solaris doesn't user
field. but we doesn't clarify that the image spec is support for
Solaris at the moment :)

As long as we have an image-spec-specific config with a user field,
I'd rather clarify it by requiring config translators to populate the
runtime-spec config's process.user for all runtime-spec OSes. Solaris
and Linux have the same runtime-spec config, so I'd expect they'd have
the same image-spec-config support.

Windows and Solaris do have memory limit, but it's not MemorySwap

As long as we continue to support an image-spec-specific MemorySwap
setting, I think it makes sense to add support for the related Solaris
and Windows fields. On the other hand, if we decide to drop
MemorySwap, then we can skip the related Solaris and Windows fields.
But it seems inconsistent to only distribute memory/swap limits if the
target OS happens to be Linux.

[vbatts]

Largely, LGTM
I am in favor of just removing Memory MemorySwap CpuShares too

[vbatts]

needs a rebase

[coolljt0725]

@vbatts rebased

[vbatts]

LGTM

[jonboulle]

lgtm for now