to_clipboard() locks clipboard system-wide on exception
Exception in the following code locks clipboard system-wide until I exit my interactive Python session:

``` python
import pandas as pd
df = pd.DataFrame.from_dict({1: u' \u2014'}, 'index')
df.to_clipboard()
---------------------------------------------------------------------------
UnicodeEncodeError                        Traceback (most recent call last)
<ipython-input-58-1f8b11f0ff98> in <module>()
----> 1 df.to_clipboard()

C:\Python27\lib\site-packages\pandas\core\generic.pyc in to_clipboard(self, excel, sep, **kwargs)
   1000         from pandas.io import clipboard
-> 1001         clipboard.to_clipboard(self, excel=excel, sep=sep, **kwargs)
   1002 
   1003     #----------------------------------------------------------------------

C:\Python27\lib\site-packages\pandas\io\clipboard.pyc in to_clipboard(obj, excel, sep, **kwargs)
     95     else:
     96         objstr = str(obj)
---> 97     clipboard_set(objstr)

C:\Python27\lib\site-packages\pandas\util\clipboard.pyc in winSetClipboard(text)
     63     try:
     64         # works on Python 2 (bytes() only takes one argument)
---> 65         hCd = ctypes.windll.kernel32.GlobalAlloc(GMEM_DDESHARE, len(bytes(text))+1)
     66     except TypeError:
     67         # works on Python 3 (bytes() requires an encoding)

UnicodeEncodeError: 'ascii' codec can't encode character u'\u2014' in position 10: ordinal not in range(128)

```

pandas 0.14.1
