verify the license situation prior to each release

This should be continually happening anyway, but immediately prior to each release we need to verify that our license situation is in order. This issue should not ever be closed, rather just move the "Fix for Version" on to the next release.

Here are some of the tasks:

A) Ensure that all supporting libraries have a corresponding license. Basically every jar file or other external package needs to have a *.license.txt file. Ensure that any license conditions are met, e.g. for some we must add an entry to NOTICE.txt, while for some others we must not. Remember to abide by the ASF guidelines (e.g. nothing more restrictive than the Apache License).

B) Scan the whole trunk repository to add missing ASF license headers to source files and to ensure that the ASF license headers have not been accidently added to external files. See etc/relicense.txt

C) Remove any author tags.