title: Not able to add policies in SAM template
body: <p>I am working on SAM template for publishing my Application in AWS Serverless repository.
  But when I try to add policies for my lambda it shows me error:
  Invalid Serverless Application Specification document. Number of errors found: 1. Errors: Resource with id [SyncPostDataFromSfLambda] is invalid. Only policy templates are supported in 'Policies' property.</p>
  
  <p>Below is the example for my SAM template:</p>
  
  <pre><code>{
      "AWSTemplateFormatVersion": "2010-09-09",
      "Transform": "AWS::Serverless-2016-10-31",
      "Description": "Deployment",
      "Resources": {
          "SyncPostDataToSfLambda": {
              "Type": "AWS::Serverless::Function",
              "Properties": {
                  "Handler": "index.handler",
                  "FunctionName": "myLambdaFunction",
                  "CodeUri": "s3 URL",
                  "Runtime": "nodejs6.10",
                  "MemorySize": 512,
                  "Policies": [
                      "AmazonDynamoDBFullAccess"
                  ],
                  "Events": {
                      "PostResource": {
                          "Type": "Api",
                          "Properties": {
                              "RestApiId": {
                                  "Ref": "API"
                              },
                              "Path": "/apipath",
                              "Method": "post"
                          }
                      }
                  }
              }
          }
      }
  }
  </code></pre>