error while referencing more than 1 jdbc driver library

[marcel-richter]

Hello,

I guess I found a little bug which blocks me from using more than 1 jdbc jar with this plugin.

Please find below an example which doesn't work.

    jdbc_streaming {
      jdbc_driver_library => "driver1.jar,driver2.jar"
    }

I found the bug in the source and it seems that a variable validation is a little to restrict.

I have prepared a merge request which could solve the issue.
Please have a look: #64