fix serverless-offline exec (#155)

* fixed serverless-offline exec

* reverted location condition change

Author: jgilbert01

index.js

@@ -131,10 +131,12 @@ class ServerlessWebpack {
 
       'before:offline:start': () => BbPromise.bind(this)
         .then(this.validate)
+        .then(this.compile)
         .then(this.wpwatch),
 
       'before:offline:start:init': () => BbPromise.bind(this)
         .then(this.validate)
+        .then(this.compile)
         .then(this.wpwatch),
 
     };