Add a "relayfee" field to getinfo.

This shows the minimum relay fee for non-free transactions in btc/kb.

The armory developers requested this so that they can prevent users from
 creating transactions that not even their local bitcoind will relay.

This also slightly reorders the getinfo output so that the fee related
 lines are grouped and changes the help text to reflect that the units
 are btc/kb.

src/rpcmisc.cpp

@@ -46,8 +46,9 @@ Value getinfo(const Array& params, bool fHelp)
             "  \"testnet\": true|false,      (boolean) if the server is using testnet or not\n"
             "  \"keypoololdest\": xxxxxx,    (numeric) the timestamp (seconds since GMT epoch) of the oldest pre-generated key in the key pool\n"
             "  \"keypoolsize\": xxxx,        (numeric) how many new keys are pre-generated\n"
-            "  \"paytxfee\": x.xxxx,         (numeric) the transaction fee set in btc\n"
             "  \"unlocked_until\": ttt,      (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
+            "  \"paytxfee\": x.xxxx,         (numeric) the transaction fee set in btc/kb\n"
+            "  \"relayfee\": x.xxxx,         (numeric) minimum relay fee for non-free transactions in btc/kb\n"
             "  \"errors\": \"...\"           (string) any error messages\n"
             "}\n"
             "\nExamples:\n"
@@ -78,10 +79,11 @@ Value getinfo(const Array& params, bool fHelp)
         obj.push_back(Pair("keypoololdest", (boost::int64_t)pwalletMain->GetOldestKeyPoolTime()));
         obj.push_back(Pair("keypoolsize",   (int)pwalletMain->GetKeyPoolSize()));
     }
-    obj.push_back(Pair("paytxfee",      ValueFromAmount(nTransactionFee)));
     if (pwalletMain && pwalletMain->IsCrypted())
         obj.push_back(Pair("unlocked_until", (boost::int64_t)nWalletUnlockTime));
+    obj.push_back(Pair("paytxfee",      ValueFromAmount(nTransactionFee)));
 #endif
+    obj.push_back(Pair("relayfee",      ValueFromAmount(CTransaction::nMinRelayTxFee)));
     obj.push_back(Pair("errors",        GetWarnings("statusbar")));
     return obj;
 }