Add CT suspend/resume to PVE API

As discussed in a previous thread, following is a patch to support container
suspend (via vzctl chkpnt) and resume (via vzctl restore).

- Added /nodes/{node}/openvz/{vmid}/status/suspend to API
- Added /nodes/{node}/openvz/{vmid}/status/resume to API
- Adapted vm_suspend/vm_resume from PVE/QemuServer.pm into PVE/OpenVZ.pm
  - Removed locking since vzctl already does this for us, and the locks
    conflict with each other (container already locked)
  - Changed monitor commands to run_command(vzctl) calls
  - Refuse to suspend if CT is offline
  - Refuse to resume if CT is online
  - vzctl does these checks as well, but it doesn't really hurt to have them

This was great, but there were artifacts in the web UI - specifically, the
task descriptions were unformatted.  So, I moved over to www/manager/Utils.js:

- Added descriptions for vzsuspend and vzresume tasks in web UI

And while I was working with the web UI anyway:

- Added suspend/resume options to CmdMenu for both OpenVZ and QEMU guests
  - Confirm suspend before proceeding
  - No confirm on resume, since it's a startup action
- Fixed OpenVZ CmdMenu shutdown and stop confirmation prompts to refer to CTs

I considered adding these options to the toolbar, but there are enough options
there already that it can get crowded quick in smaller browser windows (such
as the ones I tend to use, for screen real estate purposes), so I opted
against that.

REVISION: Between the original version of this patch and the present, mobile
support was added, so I went into www/mobile/(OpenVZ|QEMU)Summary.js and added
the suspend and resume options there as well.  No confirmation this time, since
stop and shutdown don't bother with it either in the mobile interface.

I also did a cursory search for other places where suspend/resume commands
might be useful, and added them to bin/pvectl.  If I've missed any other spots,
I'll gladly add the commands to them, as well.

Signed-off-by: Dan Hunsaker <danhunsaker@gmail.com>