Revert "temporary revert of some files, pending dedup"

This reverts commit ef5c4b716bee5c74be2c65034e034a258d048c7d.
restore slide decks removed for fosdem
t2review WIP
More work on t2 slides
Merge pull request #9 from avsm/t2review14

Merge back slide decks now that crunch has dedup support