cmd/cored: set http.Server timeouts
cmd/cored: set http.Server timeouts

Set read & write http.Server timeouts. These are arbitrary, large values
for now. I believe it should address the "too many open files" issue:

Closes chain/chainprv#1616.
Reviewers: da39a3ee5e6b4b0d3255bfef95601890afd80709@kr



chain/chain,chain/chain,chain/chain,chain/chain,chain/chain,chain/chain