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
Fixing capitalization
Making rebuild depend on ./index.html
1. Adding syllabus with point-form summary of topics to generic home page.
2. Adding links to reference guides.
3. Putting generic calendar in two-column format.
Replacing 'coffee will be served' with 'coffee break'
Added newline in numpy lesson to fix formatting
Merge pull request #500 from zonca/numpy_lesson_fix

Bugfix: added newline in numpy lesson to fix formatting
Fix rendering of code block

Also add $ to tell input from output
1. Adding `helper` field to header (like `instructor` field).
2. Updating `README.md` to explain what it's for.
3. Updating index page validator to check `helper` field.