Create first draft of Pipeline/FeatureUnion post
Clarify some sentences
Combine two paragraphs
Remove some irrelevant code to clarify example
Add links to sklearn docs
Use TransformerMixing to do fit_transform
Explain more about transformers

Pipelines and FeaturesUnions are also transformers
Add OmniGraffle file
Mention non-support of partial_fit
Add intro paragraph
Change title
Use non-sequential link annotation
Clarify some ideas