CBLT-284 add generateJavaDocs()

http://www.couchbase.com/issues/browse/CBLT-284
CBLT-284 add @exclude tags

http://www.couchbase.com/issues/browse/CBLT-284
Issue #296 do not cancel future as described in comment-42709392

changes per comment: https://github.com/couchbase/couchbase-lite-android/issues/296#issuecomment-42709392