ENH: support for msgpack serialization/deserialization

extension of #3828

```
msgpack serialization/deserialization

support all pandas objects: Timestamp,Period,all index types,Series,DataFrame,Panel,Sparse suite
docs included (in io.rst)
iterator support
top-level api support

compression and direct calls to in-line msgpack (enabled via #3828) will wait for 0.12

closes #686

In [1]: df = DataFrame(randn(10,2),
   ...:                      columns=list('AB'),
   ...:                      index=date_range('20130101',periods=10))

In [2]: pd.to_msgpack('foo.msg',df)

In [3]: pd.read_msgpack('foo.msg')
Out[3]: 
                   A         B
2013-01-01  0.676700 -1.702599
2013-01-02 -0.070164 -1.368716
2013-01-03 -0.877145 -1.427964
2013-01-04 -0.295715 -0.176954
2013-01-05  0.566986  0.588918
2013-01-06 -0.307070  1.541773
2013-01-07  1.302388  0.689701
2013-01-08  0.165292  0.273496
2013-01-09 -3.492113 -1.178075
2013-01-10 -1.069521  0.848614
```