Fixed CreateApp symbol handling

lib/pricecaster.js

@@ -137,6 +137,10 @@ class PricecasterLib {
          * @return {String} transaction id of the created application
          */
     this.createApp = async function (sender, validatorAddr, symbol, signCallback) {
+      if (symbol.length > 16) {
+        throw new Error('Symbol exceeds 16 characters')
+      }
+      symbol = symbol.padEnd(16, ' ')
       const localInts = 0
       const localBytes = 0
       const globalInts = 5