Be more explicit in LICENSE.md about exceptions to AGPLv3

[sfsinger19103]

Chris Jerdonek writes: I think this language and approach could be improved:

"The code, except as explicitly noted, is licensed under the GNU Affero General Public License Version 3 (AGPLv3). A copy of the AGPLv3 is provided in the file agplv3.txt."

The reason is that this puts the burden on the user to look for the "explicit notes," which a priori could be located anywhere in the repository. So it's not so friendly for people wanting to use the code and knowing what they're getting. It would be better if the file could say what in the repo is and isn't licensed under the various licenses that the repo might contain, without having to search the code base.

[sfsinger19103]

@nealmcb Is it correct to say that everything is AGPLv3 except for server/eclipse-project/src/main/java/us/freeandfair/corla/auth/AuthenticationInterface.java, which is AGPLv3 with a classpath exception? If not, pls suggest a revision for the line from LICENSE.md that does not burden the reader with combing through files to see where the exceptions to AGPL3 lie.

[nealmcb]

#899 has a checklist of unfinished business on the licensing changes, including references to tools/delit.pl which uses the 2-clause BSD license, and class Dotable(dict): in rla_export/main.py. There may be more.