Instance timeout and status changes - EUCA-8722

The default timeout for instances is increased from 720 minutes to 180
days. It is expected that node controller (etc) issues would be resolved
in that time, removing the need for instance restore. Instance restore
is no longer enabled by default, instead we will now restore instances
without any resources in a "zombie" state with the instance status
indicating that the instance must be retired.

The instance system status now reflects whether it is currently being
reported. For instances that are not reported the status check will
report that they are impaired. When the instance is next reported the
status will be updated to reflect that.

EUCA-8722
CloudWatch metrics for EC2 instance status - EUCA-8722

The AWS/EC2 instance status metrics (StatusCheckFailed*) are now sent to
CloudWatch along with other instance metrics.

EUCA-8722
Merge remote-tracking branch 'origin/dev/sjones/EUCA-8722' into testing