Add --include-physical flag to show-option

Signed-off-by: Shea Levy <shea@shealevy.com>
Print a warning when invoked as "charon"
Check for scheduled events when running nixops check.
Retry SQS creation on QueueDeletedRecently error.
Fix old --uuid usage in docs to -d
When the actual public IP of an instance is not the expected elastic IP, attach the expected elastic IP.
Enable logging to syslog via logging module.

Besides the program's stdout/stderr, it will also print the user who
triggered the execution as well as the whole command that was
triggered.

   May 13 19:48:27 laptop nixops[18049]: User: rbvermaa, Command: /nix/store/bjwf978h1f56hkb7c0x40msmp8865879-nixops-0/bin/.nixops-wrapped check -d wordpress
Pass overriden sys.stderr to Deployment object. Use StringIO as baseclass for the stdout/err forwarders, to make sure every file attribute/methods are implemented.
Forget to commit scripts/nixops. Don't forward log to syslog for op_scp
Pass all arguments to rollback function as named argument. Fixes #93.
Allow Nix expression paths with spaces in them

Fixes #95.
Set x86_64-linux as default system value for EC2 deployments as well. This avoid evaluating NixOS as darwin when running on Mac OS X.
Automatically set up remote building on non-Linux hosts

This allows running NixOps on platforms like Mac OS X without
requiring the user to manually set up distributed building.  Instead
we let the machines we provisioned do the builds.

Caveat: there may be a lot of unnecessary I/O.  For instance, it's not
really necessary to copy the closure back to the coordinator.  Also,
since all machines are used for remote building, we may build a
package for machine X on machine Y, copy it from Y to the coordinator,
then from the coordinator to X.
Download/unpack VirtualBox image using native Nixpkgs

This ensures that it works on non-Linux hosts.
Add process id to syslog logs: nixops[<pid>]
Set ServerAliveInterval=60 on the SSH master, to get faster feedback on network connections
Fix 'nixops stop' for VirtualBox deployments, it used to hang indefinitely. Fixes #89.
Re-attach previously attached elastic IP on starting an EC2 instance which was in stopped state. Fixes #66.
Support independent provisioning of EBS volumes

Previously, EBS volumes could only be created as part of an EC2
instance, meaning their lifetime was tied to the instance and they
could not be managed separately.  Now they can be provisioned
independently, e.g.:

  resources.ebsVolumes.bigdata =
    { name = "My Big Fat Data";
      region = "eu-west-1";
      zone = "eu-west-1a";
      accessKeyId = "...";
      size = 1000;
    };

Fixes issue #91.
EBS volumes: --check doesn't work yet