Adding new tests to increase coverage

Actually, writing a number to a file in python 2 *doesn't* work.

```bash
(2.7)nmadnani@M-AH552660 > python                                                                                   ~/work/skll
Python 2.7.8 |Continuum Analytics, Inc.| (default, Aug 21 2014, 15:21:46) 
[GCC 4.2.1 (Apple Inc. build 5577)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
Anaconda is brought to you by Continuum Analytics.
Please check out: http://continuum.io/thanks and https://binstar.org
>>> from io import open
>>> from __future__ import print_function
>>> outfile = open('xxx', 'w')
>>> print(1, end='\t', file=outfile)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: must be unicode, not str
```

Looks like python converts the number to a string and not unicode and the file expects unicode?