Outdated NOTICE.txt

Beta 2 includes a NOTICE.txt which seems to be out of date, mentioning JSCH, JTidy, and AspectJ, and not mentioning other things such as Google Collections. The situation with the proposed Beta 3 code is even worse, omitting mention of Aether or Guice.

Especially for embedded use, it would be nice to have a complete and current list of third-party software included in the Maven distribution, i.e. everything not developed inside the Maven source tree. This is not hard to determine from the JAR names but those without an internal pom.xml such as nekohtml are less obvious.