ec2nodefind: support other-region discovery

Only affects autodiscovery mode (-a)
- add new local_region which is used only by autodiscovery to detect the
  instance's service/cluster/environ.

Specifying a region with auto now autodiscovers instances in another region
ie: ec2nodefind -a -r us-west-2
Merge pull request #44 from WrathOfChris/cm-ec2nodefind-multiregion

ec2nodefind: support other-region discovery