notebook -- spurious u0027's output

<div id="comment:0"></div>

In the notebook we have this, caused by _eval_cmd in worksheet.py:

```
%python 
2+2
print "'hi\'"
///

'hi\u0027
```

Component: **notebook**

Author: **Willem Jan Palenstijn, Tim Dumol**

Reviewer: **Mitesh Patel, Tim Dumol**

Merged: **sagenb-0.8**

_Issue created by migration from https://trac.sagemath.org/ticket/3154_

