svn r172: minor RPC changes

[Gavin Andresen]

svn rev 172 (bitcoin 0.3.14.01) adds:

"testnet" and "keypoololdest" to getinfo output.  testnet will be true if you are running on the test network.
keypoololdest is the Unix timestamp of the oldest entry in the keypool.

For example:

Code:

./bitcoind getinfo
{
    "version" : 31401,
    "balance" : 100.63000000,
    "blocks" : 86925,
    "connections" : 1,
    "proxy" : "",
    "generate" : true,
    "genproclimit" : 1,
    "difficulty" : 2149.02181495,
    "hashespersec" : 998425,
    "testnet" : false,
    "keypoololdest" : 1286757166,
    "errors" : ""
}

I also made bitcoin return proper HTTP Date: headers to better follow the HTTP spec.