Some OCSP responses (notably COMODO's) don't use an intermediate
certificate to sign OCSP responses so this change allowed that.
Additionally, a CreateRequest function is added for creating OCSP
requests.
This change makes one API change: SerialNumber becomes a *big.Int to
match crypto/x509. The original code dates to before encoding/asn1
could cope with big.Ints and using a []byte was a workaround for that.
R=golang-dev
CC=golang-dev
https://golang.org/cl/10402043
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