Add (failing) test and test data which exposes an issue with leading '0' in key id

This adds a new key with an id that starts with a '0'.
Use String.format instead of Long.toHexString to create hex string of key id in getSecretKey method

Long.toHexString does not output leading zeros, which causes the comparison to
fail if the key id is something like 0ACA2060.
Merge pull request #179 from mstock/bugfix/key-id-with-leading-0

Use String.format instead of Long.toHexString to create hex string of key id in getSecretKey method