Fix channel shim test for gevent 1.0.0

Gevent 1.0 specifies this as its version, not 1.0.0, breaking the
comparison spuriously if one has version 1.0 installed exactly.
Remove redundant conditional
Implement parallelized, pipelined prefetching of WAL

This is intended to achieve a drastic performance increase in WAL
application in many situations.

This is done by using some temporary directories and daemonized
sub-processes, implement a prefetcher that can hopefully pipeline
downloading WAL to be applied while Postgres is performing other WAL
recovery.
Expand acceptable negotiated ciphers

Both AES256 and AES128 are fine. The purpose of this test was to avoid
3DES in particular.
Make lzo compression in the pipeline optional
README typo fixes
Add Sean Linsley <xovatdev@gmail.com> as a contributor