Update published javadoc

Published javadoc exists in a few places. We need to figure out where best to host it, and how to keep it up to date.

1) The javadocs as linked from the wiki page Javadoc in Git is linked to 2.3 branch of  github page grouper/doc/api/ . It was last updated in the 2.3 branch 2 years ago, and in master (no link) 5 years ago. This only includes javadoc for the api, not other projects

2) The page on http://internet2.github.io/grouper/2.2.x/grouper-parent/project-reports.html looks like what gets generated by the maven site plugin. The 2.2.2 version was updated 3 years ago, and the master version was updated one month before that.

3) The "gh-pages" branch on github was intended, I presume, to host the current master javadocs. New javadocs got built by travis on every master commit, and the results pushed to this branch. This was functioning between August 2014 and December 2016, but the travis job stopped working at that point. When I fixed the travis job a few months ago, I disabled the gh-pages generation. The reason was that every generated html file included a timestamp in hidden code, so that 2600+ files got commited for every master commit. This seemed excessive, plus git tools were useless because github refused to show a commit with so many files changed.