message: increase max fee rate to 150 sat/byte
  Summary: the time for a tx to be confirmed in 2 blocks is currently around 115 sat/byte, so we increase this upper threshold
  Reviewers: benchan, ben
  Subscribers: ben
diff: @@ -1454,9 +1454,9 @@ BitGo.prototype.getConstants = function(params) {
  // TODO: once server starts returning eth address keychains, remove bitgoEthAddress
  var defaultConstants = {
  maxFee: 0.1e8,
  - maxFeeRate: 100000,
  - minFeeRate: 2000,
  - fallbackFeeRate: 20000,
  + maxFeeRate: 250000,
  + minFeeRate: 1000,
  + fallbackFeeRate: 50000,
  minOutputSize: 2730,
  bitgoEthAddress: '0x0f47ea803926926f299b7f1afc8460888d850f47'
  };
  