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
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
Fix rendering of code block

Also add $ to tell input from output
Converting to individual challenge div's in the novice shell lessons
Converting to single-div-per-challenge in novice Git tutorial
Bugfix: code block not rendering in 02-func
Bugfix: code blocks not rendering in novice/python/03-loop
Bugfix: code block not rendering in novice/python/04-cond
Merge pull request #501 from zonca/formatting_fixes

Bugfix: fix rendering of code block
Bugfix: missing file `fractal_1.txt` replaced with `small-01.csv`
Refer to rescale() instead of center()