STY: Fix flake8 errors

Most of them were very minor, fixes #547.
Indeed.

```python
In [2]: def o():
   ...:     c = [9000]
   ...:     c.extend([1] * 1000)
   ...:     counts = np.array(c)
   ...:     

In [3]: def n():
   ...:     counts = np.ones(1001)
   ...:     counts[0] = 9000
   ...:     

In [4]: import numpy as np

In [5]: %timeit o()
10000 loops, best of 3: 116 µs per loop

In [6]: %timeit n()
100000 loops, best of 3: 4.47 µs per loop
```


On (Jul-22-14| 6:43), adamrp wrote:
> > @@ -26,9 +26,9 @@ def create_fake_observation():
> >      # Create a subsample of a larger sample such that we can compute
> >      # the expected probability of the unseen portion.
> >      # This is used in the tests of lladser_pe and lladser_ci
> > -    x = [9000]
> > -    x.extend([1] * 1000)
> > -    counts = np.array(x)
> > +    c = [9000]
> > +    c.extend([1] * 1000)
> > +    counts = np.array(c)
> 
> While we're looking at this code, we might as well change this to the simpler/faster
> ```python
> counts = np.ones(1001)
> counts[0] = 9000
> ```
> 
> ---
> Reply to this email directly or view it on GitHub:
> https://github.com/biocore/scikit-bio/pull/548/files#r15227890