PERF: frame_repr_wide benchmark
Is this correct? (on current master)

```
In [1]: df = pandas.DataFrame(np.random.randn(10,10000))

In [2]: %timeit repr(df)
1 loops, best of 3: 9.85 s per loop

n [4]: pandas.__version__
Out[4]: '0.12.0.dev-a62ea81'
```

```
%prun repr(df)

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
  1920528    1.310    0.000    1.710    0.000 re.py:226(_compile)
  1119307    1.253    0.000    1.724    0.000 StringIO.py:208(write)
  1920528    1.092    0.000    1.092    0.000 {method 'search' of '_sre.SRE_Pattern' objects}
  1920528    1.069    0.000    3.870    0.000 re.py:139(search)
   210010    1.026    0.000    1.763    0.000 format.py:1537(just)
    80022    0.884    0.000    5.224    0.000 config.py:455(_select_options)
    60003    0.782    0.000    0.782    0.000 {method 'reduce' of 'numpy.ufunc' objects}
  1940531    0.403    0.000    0.403    0.000 {method 'get' of 'dict' objects}
    80022    0.402    0.000    0.402    0.000 {sorted}
   530020    0.345    0.000    0.345    0.000 {_codecs.utf_8_decode}
```
