title: How to use filter on query_entities
body: <p>I want to use a filter on query_entities for Azure table storage.</p>
  
  <p>I have tried to use filter like this : 
  Table = table_service.query_entities('MyTableName', filter = "RowKey eq 20")</p>
  
  <pre><code>#coding:utf-8
  import os
  import json
  from azure import *
  from azure.storage import *
  from azure.storage.table import TableService, Entity
  
  table_service = TableService(account_name='MyAccountName', 
  sas_token='MySASToken')
  Table  = table_service.query_entities('MyTableName', filter = "Country eq 
  USA")
  print(Table.items)
  </code></pre>
  
  <p>I got an exception:</p>
  
  <blockquote>
    <p>azure.common.AzureHttpError: Bad Request
    {"odata.error":{"code":"InvalidInput","message":{"lang":"en-US","value":"A
    binary operator with incompatible types was detected. Found operand
    types 'Edm.String' and 'Edm.Int32' for operator kind
    'Equal'.\nRequestId:ef3858e7-5002-00d0-617f-0d374a000000\nTime:2019-05-18T13:45:23.6288160Z"}}}</p>
  </blockquote>
  
  <p>And I have tried changing to this : </p>
  
  <pre><code>Table  = table_service.query_entities('MyTableName', filter = "Country eq 
  USA")
  </code></pre>
  
  <p>But I get SyntaxError: invalid syntax</p>