chore: update big number package

lib/plugins/ticker/bitpay.js

@@ -11,7 +11,7 @@ function ticker (fiatCode, cryptoCode) {
   return axios.get('https://bitpay.com/rates/' + cryptoCode + '/' + fiatCode)
     .then(r => {
       const data = r.data.data
-      const price = BN(data.rate.toString())
+      const price = new BN(data.rate.toString())
       return {
         rates: {
           ask: price,

lib/plugins/ticker/ccxt.js

@@ -40,8 +40,8 @@ function getCurrencyRates (ticker, fiatCode, cryptoCode) {
     return ticker.fetchTicker(symbol)
       .then(res => ({
         rates: {
-          ask: BN(res.ask),
-          bid: BN(res.bid)
+          ask: new BN(res.ask),
+          bid: new BN(res.bid)
         }
       }))
   } catch (e) {
@@ -52,7 +52,7 @@ function getCurrencyRates (ticker, fiatCode, cryptoCode) {
 function findCurrencyRates (fxRates, fiatCode) {
   const rates = _.find(_.matchesProperty('code', fiatCode), fxRates)
   if (!rates || !rates.rate) throw new Error(`Unsupported currency: ${fiatCode}`)
-  return BN(rates.rate.toString())
+  return new BN(rates.rate.toString())
 }
 
 module.exports = { ticker }

lib/plugins/ticker/mock-ticker.js

@@ -3,8 +3,8 @@ const BN = require('../../bn')
 function ticker (fiatCode, cryptoCode) {
   return Promise.resolve({
     rates: {
-      ask: BN(105),
-      bid: BN(100)
+      ask: new BN(105),
+      bid: new BN(100)
     }
   })
 }