Automatically creating file queue directories for Queue4client

[g9yuayon]

The current Queue4Client swallows IOException if the given file queue path does not exist. This will lead to NullPointerException later, making debugging hard. The fix is as follows:

• IOException will be wrapped into an IllegalStateException and re-thrown
• If a given file queue path is not a directory, an IllegalStateException will be thrown
• If a given file queue path does not exists, the Queue4Client will try to create the full path. If the attempt to create the path fails, an IllegalStateException will be thrown

[cloudbees-pull-request-builder]

suro-pull-requests #85 SUCCESS This pull request looks good