v2.1.0 add config option, add supporting to "Expires" tag

Now command-line can take configuration path parameter. This makes multiple EBS attachment possible.
Now volumes/snapshots can be tagged(manually) with "Expires" with a readable timestamp ("2018-03-19 07:06:15.712000+00:00" as an example, or a epoch second, or Never). Deleting old resources will respect this tag.

Release 2.0.0, with a newly implemented ebs-pin

This adds more protection than the original ebs-pin.