Fix wallet issues!

[Twente-Mining]

https://bitcointalk.org/index.php?topic=2710157.msg28031251#msg28031251

[phm87]

When I compare TZC and SGL getinfo, value of paytxfee is set to 0.01 for TZC but 0 for SGL, I think that it is the root-cause of failed payment. TZC is running fine on our pool.

Payments of SGL were successfull when min payout manually set to 0.01 in the mining pool. paytxfee should have done the job, this trick is a work-around, please don't close this issue without code change.

I think that we should search for MIN_TX_FEE or COIN.

To change (at least to have behavior similar to TZC):
./trezarcoind getinfo
{
"version" : "v1.0.0.0-trz-2-ge971550-dirty",
"protocolversion" : 60016,
"walletversion" : 60000,
"balance" : ,
"stake" : 0.00000000,
"newposmint" : 0.00000000,
"newpowmint" : ,
"allposmint" : 0.00000000,
"allpowmint" : ,
"blocks" : 199214,
"timeoffset" : -1,
"moneysupply" : 99920400.00000000,
"connections" : 52,
"proxy" : "",
"ip" : "",
"keypoololdest" : 1515830710,
"keypoolsize" : 101,
"paytxfee" : 0.01000000,
"mininput" : 0.00100000,
"testnet" : false,
"errors" : ""
}
./sigild getinfo
{
"version" : "v1.0.0.0-orb",
"protocolversion" : 60016,
"walletversion" : 60000,
"balance" : ,
"stake" : 0.00000000,
"newposmint" : 0.00000000,
"newpowmint" : 0.00000000,
"allposmint" : 0.00000000,
"allpowmint" : ,
"blocks" : 21768,
"timeoffset" : 0,
"moneysupply" : 3043715.00000000,
"connections" : 10,
"proxy" : "",
"ip" : "",
"keypoololdest" : 1516304667,
"keypoolsize" : 101,
"paytxfee" : 0.00000000,
"mininput" : 0.00100000,
"testnet" : false,
"errors" : ""
}

[UniMiningNet]

#2 won't fix all problems but payments will be fine on mining pools with low mininum payouts.

As discussed with ocminer, the problem is not the fee: the wallet tries to send unmature pos coins - even if pos is disabled completely. TZC has the same problem and FTC also.

[Twente-Mining]

if that is the case, fix that problem, the bug being elsewhere isn't an excuse to leave it in.
Thanks for addressing this fee problem