changed celery version

@jakul changed celery version. without this, with Django 1.4 it will install a more recent version of celery `3.1.1` that has some import errors and wont alow my `supervisorctl` to start/restart:

```
Traceback (most recent call last):
  File "/src/networklocum/networklocum/manage.py", line 14, in <module>
    execute_manager(settings)
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 459, in execute_manager
    utility.execute()
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 261, in fetch_command
    klass = load_command_class(app_name, subcommand)
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 69, in load_command_class
    module = import_module('%s.management.commands.%s' % (app_name, name))
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/django/utils/importlib.py", line 35, in import_module
    __import__(name)
  File "/home/administrator/.virtualenvs/networklocum/local/lib/python2.7/site-packages/djcelery/management/commands/celerycam.py", line 8, in <module>
    from celery.bin import celeryev
ImportError: cannot import name celeryev
```