Export escape function on serverless-mysql

Author: wviveiro

index.d.ts

@@ -100,6 +100,7 @@ declare namespace serverlessMysql {
     config(config?: MySQL.ConnectionConfig): MySQL.ConnectionConfig
     query<T>(...args): Promise<T>
     end(): Promise<void>
+    escape(str: string): MySQL.EscapeFunctions
     quit(): void
     transaction(): Transaction
     getCounter(): number

index.js

@@ -373,16 +373,18 @@ module.exports = (params) => {
   onKillError = typeof cfg.onKillError === 'function' ? cfg.onKillError : () => {}
 
   let connCfg = typeof cfg.config === 'object' && !Array.isArray(cfg.config) ? cfg.config : {}
-
+  let escape = MYSQL.escape
   // Set MySQL configs
   config(connCfg)
 
+
   // Return public methods
   return {
     connect,
     config,
     query,
     end,
+    escape,
     quit,
     transaction,
     getCounter,