Previously, if Encrypt decided to use a hash function that wasn't
compiled in then it would panic.
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12055043
Manual edits to README.
Moved from main Go repository, deleted Makefiles, ran gofix -r go1rename.
Tested with: go test code.google.com/p/go.crypto/...
R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5564059