Sort the lists of notice files instead of relying on the filesystem
ordering returned by os.walk
Bug: 23972440
Change-Id: Id32be9ce8e540244ad9d67b6fc7883fc2963fe5c
(it was getting fairly complicated in bash),
update HTML output to have a table of contents,
and fix typos/bugs in notice file CSS
Change-Id: I51131f594e3bbe63f03165fa42f5ceeaec518543