Use a string in the deviceID

[ElodieLam]

This request is related to my previous suggestion https://github.com/Dynatrace/openkit-java/issues/207

Would it be possible to use a string in the deviceID? In my customer context, every user is identified with a unique string identifier (Ex. Z1234567) or with the “Hostname” (Ex. INHL0007777) which are unfortunately alpha numeric characters.

Thank you!