First version of sklearn intro IPython Notebook
Removed lesson number
Added an outline

Also removed a cell
Print number of samples in the dataset
Use StandardScaler instead of scale

For simplicity just scale all of the dataset for
grid search.
see: https://github.com/swcarpentry/bc/pull/443#issuecomment-40677511
Optimize max_features instead of n_estimators

Useless to estimate n_estimators, the more the better!
Use a Pipeline to add feature scaling
Removed feature scaling, expanded acronym RMS

Feature scaling is not necessary for Decision Tree and Random Forests:
https://github.com/swcarpentry/bc/pull/443#issuecomment-41324381
first draft of SSH keys for GitHub lesson
Remove import of Pipeline
added conclusion
Replaced Iris example

Iris example was not clear, replaced with another example.
Added also svg and Google Docs url.

Minor changes:
* explain del rings
* removed download of dataset, just link
remove OSX specific pbcopy, remove passphrase material, explain random art image
Fix headings for book

Some Markdown files start with

    ---
    layout: lesson
    root: .
    title: TITLE
    ---
    ### SUBTITLE

When creating `book.md` it will have

    ## TITLE
    ### SUBTITLE

that is translate into HTML by Jekyll as

    <h2>TITLE</h2>
    <p>### SUBTITLE</p>

Change `make-book.py` to generate `book.md` having

    ## TITLE

    ### SUBTITLE

will fix this issue without side effect.

Thanks to @jduckles for reporting this issue.
removed mention of for loop

Following up 2014-06-24-wise-penn/#2 It had been commented out here, and to minimise confusion I've deleted it completely. Loops come in lesson three (this is lesson one), so I think it's safe to exclude it from here.
removed mention of for loop

making the md file consistent with the Rmd file
Merge pull request #545 from r-gaia-cs/fix-book-h2

Fix headings for book
Fixes #546 by using level-3 headings in all Markdown source files for subsections.
We continue to use level-4 headings for objectives, key points, callout boxes, and challenges.
Fix more level 3 headings
Merge pull request #548 from gvwilson/using-level-3-headings-for-subsections-in-markdown

Using level-3 headings in Markdown files for subsections.