Add Pond server setup documentation
Go 1.0 needs return statements.
cli.go uses the TPM-related message strings.

Needed when building with -tags nogui.
Update to account for changes in the ed25519 package.
Merge branch 'ln5-fixes'
Fixes to the "running a server" documentation.
Merge branch 'david415-david-server-setup-docs'
Get CLI working on OS X.
CLI tweaks and cleanups.
cli: Don't print an empty line after an empty table.
Add a user guide for the CLI.
Use cliTable for printing help in the CLI.
Discare pure acks from the inbox.

With this change, pure ack messages (those with an empty Body) will be
discarded after processing and no longer kept in the inbox.
Ensure that go failures don't leak server processes.

It was previously possible, if one hit a panic in a test, to have server
processes hanging around afterwards.

This change installs a lifeline file descriptor in the server process so
that, when the kernel cleanup up the test process, the server will see
EOF and can exit.
Decreased maxMissingMessages. Substantially. This has a negative impact on safety under message reordering; but it substantially decreases the window an attacker who obtains access to Pond's state can forge messages.