Make sure to print a time zone when formatting even if none is defined.
Add a comment introducing lookupTimezone (not lookupTimeZone).
Fixes isse 577.
R=rsc
CC=golang-dev
https://golang.org/cl/196090
The model is that formatString is a a representation of a standard time,
and that Format converts the time to that representation.
Standard representaitons are defined for ANSIC, RFC850, RFC1123, and ISO8601.
There's also a humane Kitchen fomat: 3:04PM.
R=rsc, benolive, cw
CC=golang-dev
https://golang.org/cl/181130