Region Copy: -g and -d options to tag and initiate region copies

-g tested with new backups using:

bash ec2-automate-backup.sh -v 'vol-8a1a43f6 vol-2a78d459' -g 'us-west-1 us-west-2' -n

-d tested with various options and repeated calls to test
idempotent copies:

bash ec2-automate-backup.sh -s regioncopy -d 'us-west-1'
bash ec2-automate-backup.sh -s regioncopy -d 'us-west-1'
bash ec2-automate-backup.sh -s regioncopy -d 'us-west-1 us-west-2'
bash ec2-automate-backup.sh -s regioncopy -d 'us-west-2'

etc.
Region Copy: Mac cut doesn't have --output-delimiter, use tr instead
Region Copy: Modified prerequisite_check for conditional usage
Region Copy: Updated README with new features
Merge pull request #25 from davestern/copy-volume-regional

Copy Snapshots to different regions