Some Bitswap Refactoring

This PR Includes

-making a clarifying comment on why we are currently using AlwaysSendtoPeer as a BS strategy
-re-ordering functions so that types are above functions (looks cleaner)
-There was a TODO regarding using float64 in the strategy that could've resulted in a lock, avoiding the lock
-We were using nice as a word for how we view other peers, changed that to 'trusted'. We want to bitswap to be an auction that involves trust-the strategy should vary based on how trustworthy we are, and how much we trust the peer. 
@llSourcell ... why did you introduce a constant seed? This is wrong. `rand.Float64` will draw from the default source, which we can initialize with a _**random**_ seed using `rand.Seed`.