ENH: other join types than 'left' for .update
Running 0.15.1

```
DataFrame.update(other, join='left', overwrite=True, filter_func=None, raise_conflict=False)
    Modify DataFrame in place using non-NA values from passed DataFrame. Aligns on indices

    Parameters :    
    other : DataFrame, or object coercible into a DataFrame
    join : {‘left’, ‘right’, ‘outer’, ‘inner’}, default ‘left’
```

But..

```
C:\Anaconda\lib\site-packages\pandas\core\frame.pyc in update(self, other, join, overwrite, filter_func, raise_conflict)
   3292         # TODO: Support other joins
   3293         if join != 'left':  # pragma: no cover
-> 3294             raise NotImplementedError("Only left join is supported")
   3295 
   3296         if not isinstance(other, DataFrame):

NotImplementedError: Only left join is supported
```
