This is Go 1 package renaming CL #3.
This one merely moves the source; the import strings will be
changed after the next weekly release.
This one moves pieces into net.

http -> net/http
http/cgi -> net/http/cgi
http/fcgi -> net/http/fcgi
http/pprof -> net/http/pprof
http/httptest -> net/http/httptest
mail -> net/mail
rpc -> net/rpc
rpc/jsonrpc -> net/rpc/jsonrpc
smtp -> net/smtp
url -> net/url

Also remove rand (now math/rand) from NOTEST - it has a test.

The only edits are in Makefiles and deps.bash.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5335048