Rename PoET simulator to PoET CFT

Change "PoET-sim" and "PoET simulator" to PoET CFT (with explanation of what CFT means). This change should be made throughout the Sawtooth core docs, Sawtooth website, FAQ, and Hyperledger Sawtooth pages (wiki, etc.). 

Note that the glossary must continue to include an entry for PoET simulator/PoET-sim, because it's used in blog posts, announcements, on chat.hyperledger.org, and elsewhere.

Also consider whether PoET-SGX should be renamed or "also called" PoET BFT.  In any case, the docs need a better description of the CFT/BFT differences in PoET 1.0.