Use archive/zip instead of 7z on Windows.
Look for all Windows deps before starting build, and include looking
for them in their common locations instead of making users update
their PATHs.
Add an --upload flag that, if set to false, doesn't require credential
files.
R=golang-dev, alex.brainman, adg
CC=golang-dev
https://golang.org/cl/5794046
fix, and shrink, the gopher icon, txt extensions
for license and readme files, minor format changes
in the wxs file
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5683054
