title: Python Linked API throwing error with Python 2.7
body: <p>This code to fetch skills from linkedin is working fine with python 2.6</p>
  
  <pre><code>from linkedin import helper
  from liclient import LinkedInAPI
  import json
  AUTH_TOKEN='{"oauth_token_secret": "TOKEN SECRET", "oauth_authorization_expires_in": "0", "oauth_token": "OAUTH TOKEN", "oauth_expires_in": "0"}'
  consumer_key = 'CONSUMER KEY'
  consumer_secret = 'CONSUMER SECRET'
  APIClient =LinkedInAPI(consumer_key, consumer_secret)
  request_token = APIClient.get_request_token()
  field_selector_string = ['skills']
  results = APIClient.get_user_profile(json.loads(AUTH_TOKEN), field_selector_string)
  Skills = results[0].skills
  print  Skills
  </code></pre>
  
  <p>But when I run same code with python 2.7 gettting this error</p>
  
  <pre><code>Traceback (most recent call last):
  File "linkedintest.py", line 10, in &lt;module&gt;
  results = APIClient.get_user_profile(json.loads(AUTH_TOKEN), field_selector_string)
  File "/var/www/shine/liclient/__init__.py", line 82, in get_user_profile
  resp, content = client.request(url, 'GET')
  File "/var/www/shine/liclient/oauth2/__init__.py", line 603, in request
  req.sign_request(self.method, self.consumer, self.token)
  File "/var/www/shine/liclient/oauth2/__init__.py", line 357, in sign_request
  self['oauth_signature'] = signature_method.sign(self, consumer, token)
  File "/var/www/shine/liclient/oauth2/__init__.py", line 683, in sign
  hashed = hmac.new(key, raw, sha)
  File "/usr/lib/python2.7/hmac.py", line 133, in new
  return HMAC(key, msg, digestmod)
  File "/usr/lib/python2.7/hmac.py", line 72, in __init__
  self.outer.update(key.translate(trans_5C))
  TypeError: character mapping must return integer, None or unicode
  </code></pre>