fix installation issues

Unable to install using `pip install tarantool-queue`.

Supplied patch with fix for `setup.py`. `setup.py` parse `__init__.py` to find a version.

```
$ pip install tarantool-queue
Downloading/unpacking tarantool-queue
  Downloading tarantool-queue-0.1.1.tar.gz
  Running setup.py (path:/Users/e.iskandarov/.virtualenvs/t1/build/tarantool-queue/setup.py) egg_info for package tarantool-queue
    Traceback (most recent call last):
      File "<string>", line 17, in <module>
      File "/Users/e.iskandarov/.virtualenvs/t1/build/tarantool-queue/setup.py", line 6, in <module>
        from tarantool_queue import __version__
      File "tarantool_queue/__init__.py", line 3, in <module>
        from tarantool_queue import Task, Tube, Queue
      File "tarantool_queue/tarantool_queue.py", line 4, in <module>
        import msgpack
    ImportError: No module named msgpack
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):

  File "<string>", line 17, in <module>

  File "/Users/e.iskandarov/.virtualenvs/t1/build/tarantool-queue/setup.py", line 6, in <module>

    from tarantool_queue import __version__

  File "tarantool_queue/__init__.py", line 3, in <module>

    from tarantool_queue import Task, Tube, Queue

  File "tarantool_queue/tarantool_queue.py", line 4, in <module>

    import msgpack

ImportError: No module named msgpack

----------------------------------------
Cleaning up...
```