message: Pass gasprice with wallet create
  Summary: For ethereum, users should be able to pass gasprice with the wallet generate call
  Reviewers: tyler, bigly, arik
  Subscribers: ben
diff: @@ -181,6 +181,7 @@ Wallets.prototype.add = function(params, callback) {
  * @param params.disableTransactionNotifications
  * @param params.passcodeEncryptionCode
  * @param params.coldDerivationSeed
  + * @param params.gasPrice
  * @param callback
  * @returns {*}
  */
  @@ -297,15 +298,28 @@ Wallets.prototype.generateWallet = function(params, callback) {
  };
  }
  - if (params.enterprise) {
  + if (!_.isUndefined(params.enterprise)) {
  + if (!_.isString(params.enterprise)) {
  + throw new Error('invalid enterprise argument, expecting string');
  + }
  walletParams.enterprise = params.enterprise;
  }
  - if (params.disableTransactionNotifications) {
  + if (!_.isUndefined(params.disableTransactionNotifications)) {
  + if (!_.isBoolean(params.disableTransactionNotifications)) {
  + throw new Error('invalid disableTransactionNotifications argument, expecting boolean');
  + }
  walletParams.disableTransactionNotifications = params.disableTransactionNotifications;
  }
  - if (self.baseCoin.getFamily() === 'xrp' && params.rootPrivateKey) {
  + if (!_.isUndefined(params.gasPrice)) {
  + if (!_.isNumber(params.gasPrice)) {
  + throw new Error('invalid gas price argument, expecting number');
  + }
  + walletParams.gasPrice = params.gasPrice;
  + }
  +
  + if (self.baseCoin.getFamily() === 'xrp' && !_.isUndefined(params.rootPrivateKey)) {
  walletParams.rootPrivateKey = params.rootPrivateKey;
  }
  @@ -323,11 +337,11 @@ Wallets.prototype.generateWallet = function(params, callback) {
  bitgoKeychain: bitgoKeychain
  };
  - if (backupKeychain.prv) {
  + if (!_.isUndefined(backupKeychain.prv)) {
  result.warning = 'Be sure to backup the backup keychain -- it is not stored anywhere else!';
  }
  - if (derivationPath) {
  + if (!_.isUndefined(derivationPath)) {
  userKeychain.derivationPath = derivationPath;
  }
  