Fixes https://github.com/tendermint/tendermint/issues/851
Go1.9 and below's net.Pipe did not implement the SetDeadline
method so after commit
e2dd8ca946
this problem was exposed since now we check for errors.
To counter this problem, implement a simple composition for
net.Conn that always returns nil on SetDeadline instead of
tripping out.
Added build tags so that anyone using go1.10 when it is released
will be able to automatically use net.Pipe's net.Conns
Emmanuel Odeke