Fails to parse EBS volume ARN

[schosterbarak]

Value like:
"arn:aws:us-west-2:XXX:volume/YYY"
Replace XXX with account-id ad YYY with volume-id
throws

[ERROR] IndexError: list index out of range
  File "/var/task/arnparse/arnparse.py", line 30, in arnparse
    resource = elements[5]

[schosterbarak]

Suggested fix: #9 @spg would you mind taking a look?

[laurrentt]

@schosterbarak I saw that you've closed the issue. Do you mind closing the Pull Request as well? Thank you 🙂