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
Fix TypeError in build_configs
Add provisioning of elastic IP addresses

Example:

  resources.elasticIPs."nixos.org" =
    { region = "eu-west-1";
      accessKeyId = "...";
    };
Fix message
Retry creation of snapshot, as it might run into a RequestLimitExceeded.
New AMIs.
When attaching an EBS volume, first wait until EBS API has the volume
in 'attached' state.  This will ensure that we catch situation where
volumes are in weird states (e.g. attaching). Use log functions for
'wait' functions to have nicer logs output.
Extended 'nixops check' to take into account the attachment status of EBS volumes.

+---------+--------+-----+-----------+----------+----------------+--------------+-------------------------------------------------------------------------------+
| Name    | Exists | Up  | Reachable | Disks OK | Load avg.      | Failed units | Notes                                                                         |
+---------+--------+-----+-----------+----------+----------------+--------------+-------------------------------------------------------------------------------+
| machine | Yes    | Yes | Yes       | No       | 0.00 0.01 0.05 |              | volume ‘vol-34baca6f’ on device ‘/dev/xvdf’ has unexpected state: ‘attaching’ |
+---------+--------+-----+-----------+----------+----------------+--------------+-------------------------------------------------------------------------------+
Perform remote builds on a single machine

Fixes issue #103.
Allow restoring to an EC2/EBS backup for a subset of devices (e.g. just data disk on /dev/xvdf). Also added --backup-id argument as the previous positional argument was incompatible with usage of --exclude/--include.