peerstore: re-export ErrNotFound

This is to avoid having to import ds elsewhere.
spipe + handshake with peerstore
update net with peerstore
ammend tests with changes
increment time for queue test

it's failing when machine slow (travis)
ok fixed queue test
fixed muxer errors
set util.ErrNotFound = ds.ErrNotFound
remove stale TODO
handshake catch
crypto: abstracted Key and added Equals.
Merge pull request #128 from jbenet/feat/peerstorefix

Peerstore Fix