(MAINT) broken spec fixes (docker + copy_module_to)

- docker spec was still allowing sleeps to execute making things run
  slow
- update copy_module_to spec test to use correct ignore list
Merge pull request #451 from anodelman/maint

(MAINT) broken spec fixes (docker + copy_module_to)
(MAINT) add ability to list all instances associated with an ec2 keyname

- convenience function for listing all instances associated with a
  provided keyname, useful for tracking what's happening in ec2