DOC: Clean up Sphinx Issues, fix tabs, in Cookbook

This is a follow on PR as a result of [seeing travis and sphinx render ~30 in line examples for the cookbook] (https://github.com/pydata/pandas/pull/8288#issuecomment-58734824).

Continues to address #6918

Initial PR: https://github.com/pydata/pandas/pull/8288

PS - apologies for wanting to rush the first PR.  My evening opened up unexpectedly.  Feel free to merge this latest, or provide more feedback for me to work on later. I'm going off grid for 2+ days starting oct 10th 11 PM EST.

The latest rendering is [here](https://cloud.githubusercontent.com/assets/6062071/4601203/f3dcdc76-50f0-11e4-8466-4db698bdc3b4.png):

![pandascookbook4](https://cloud.githubusercontent.com/assets/6062071/4601203/f3dcdc76-50f0-11e4-8466-4db698bdc3b4.png)
This codeblock was a hack to get sphinx to render it.  It rendered fine on my local machine, then didn't on [github.io](http://pandas-docs.github.io/pandas-docs-travis/cookbook.html)

Did you see my last comment on PR #8288 ? It shows the problem that this codeblock / hack solved.   Note the significant digits of the floats.  It renders just the most significant figure, '1', on github.io but on my local machine there is 4 or 5 significant figures.

I have no way of testing solutions, other than attempting a another commit, merging it, then having it build.  I can't even guess at how I might get sphinx/gitbhub.io to render it properly. We could kill the example, but that feels like a wasted, since this commit fixes it via the hard coded, coding block.