title: Getting an Ebay OAuth Token
body: <p>I've been working on the ebaySDK for most of the week. I've managed to integrate the Trading and Shopping APIs into my project. For the trading API, I was using an Auth n Auth token which has a validity of upto 18 months. The OAuth Token which I need for the Sell APIs is valid only for a day, so I'll need to fetch it regularly before it expires. 
  I followed the documentation on the site and even tried looking through python repos on github but I haven't been able to move forward as of yet. Here's a quick snippet of my request code, What am I doing wrong? </p>
  
  <pre><code>import requests, json, base64, xmltodict
  
  AppSettings = {
      'app_id' : 'my_app_id',
      'app_secret' : 'my_app_secret',
      'dev_id': 'my_dev_id',
      'ruName': 'the_ruName_for_my_app'
  }
  authHeaderData =  AppSettings['app_id']+':'+AppSettings['app_secret']
  encodedAuthHeader = base64.b64encode(authHeaderData)
  
  session = requests.Session()
  
  print encodedAuthHeader 
  url = 'https://api.ebay.com/identity/v1/oauth2/token'
  
  session.headers.update({
      'Content-Type':'application/x-www-form-urlencoded',
      'Authorization':'Basic '+encodedAuthHeader
      })
  
  data = {
      'grant_type':'client_credentials',
      'redirect_uri': AppSettings['ruName'],
      'scope':'https://api.ebay.com/oauth/api_scope'
  }
  
  response = session.post(url, data=data).json()
  print response
  </code></pre>
  
  <p>The response I'm getting is:</p>
  
  <pre><code>{u'error_description': u'client authentication failed', u'error': u'invalid_client'}
  </code></pre>
  
  <p>I checked all the keys. I even tried to get the token via the production signin provided by ebay but to no avail. The response I got from the url provided by ebay was html and js code (No JSON or any data). </p>
  
  <p>Has anybody faced a similar issue? How can I work through this? Am I making the requests wrong? Any insight is greatly appreciated</p>