readme: changed Go requirement to 1.2+ due to recent changes in memberlist.
changelog: mention Go 1.2+ requirement when building from source.
Merge pull request #44 from mcroydon/doc-go-12

Mention Go 1.2+ requirement in README and CHANGELOG.
serf: update to new Memberlist delegate interface
serf: adding EventMinTime to filter events
serf: adding ignoreOld flag to join
serf: split coalesce and make use of interface
serf: UserEvent exposes the lamport time
serf: supporting user event coalescing
serf: support enable/disable coalesce on per-message basis
website license
don't think we need to mention Go 1.2 in CHANGELOG

THe CHANGELOG is mostly for user-level features, and I don't think the
requirement for Go 1.2 really changes anything for end users.
website: fix typo

Courtesy of @jefflab
serf: expose a protocol version from Serf
serf: keep track of the protocol verisons of each member
command/agent: can specify the protocol config
command/agent: fix docs
command: add protocol to version command
command: add "-detailed" to `serf members` to see the protocol versions
website: document the protocol versions