to_clipboard(excel=False) truncates strings to 50 characters
I hope this is not intended as I can't find the point in this behavior:

``` python
import pandas as pd
df = pd.DataFrame.from_dict({1: ''.join(['1234567890'] * 6)}, 'index')
df.to_clipboard(excel=False)
```

result copied to clipboard:

```
                                                   0
1  1234567890123456789012345678901234567890123456...
```

Another issue - trying to omit index:

``` python
df.to_clipboard(excel=False, index=False)
```

result copied to clipboard, just the same as previous (with index):

```
                                                   0
1  1234567890123456789012345678901234567890123456...
```

This doesn't happen if I leave `excel` parameter to default value.
