Clarify license

[kwin]

Due to the two conflicting licenses at

• https://github.com/codehaus-plexus/plexus-classworlds/blob/plexus-classworlds-2.7.0/LICENSE.txt and
• https://github.com/codehaus-plexus/plexus-classworlds/blob/master/LICENSE-Codehaus.txt

GitHub cannot figure out the correct license (i.e. the badge at https://github.com/codehaus-plexus/plexus-classworlds/blob/master/README.md says "not identifiable").

In the pom.xml it just inherits the license from the parent pom: https://github.com/codehaus-plexus/plexus-pom/blob/2a37f7e5329e194656339384e5ceba60714d8b0d/pom.xml#L36

But the site has an an empty license body in https://codehaus-plexus.github.io/plexus-classworlds/licenses.html.

[kwin]

But the site has an an empty license body in https://codehaus-plexus.github.io/plexus-classworlds/licenses.html.

This should probably be fixed by codehaus-plexus/plexus-pom@a9d1aad as it seems GitHub rather uses the pom.xml for the license badge (https://github.com/badges/shields/blob/master/services/github/github-license.service.js).

[cuixinye]

1, The license header of java files were changed to Apache-2.0 with this commit 8417bcd. But the LIECNSE.txt in root directory was kept unchanged.
2, Apache-2.0 was added to pom.xml with commit aa37242 and it keeps to now.
3, Commit fb238e6reverted commit 8417bcd. But pom file kept unchanged with apache-2.0 statement.
4, With this commit 97ca63b, things get interesting. It said "added missing copyright header", but it added apache-2.0 header, not Plexus.
5, Maby because of that commit, Apache 2.0 license file LICENSE-2.0.txt was added to root directory with commit 9c935ad. Later its name was changed to LICENSE.txt till now.
That's the timeline I find. From Fedora Notes, Plexus Classworlds License is derived from Apache 1.1. So please consider to update license to Apache 2.0. There is no need to use an old and uncommon license. @slachiewicz