Add pattern examples

[benjamingr]

Start work on adding pattern examples.

I will post here examples of many common promise patterns, idioms and anti patterns.

[thefourtheye]

+1. I love the idea of documenting knowledge like this.

[chrisdickinson]

A few naming nits: Do you mind changing patterns to examples? I'd like to add examples for post-mortem and async/await use as well, and some of those topics don't fit neatly under the term "patterns". In that vein, would you mind either prefixing these files with promise- or nesting them into a promise sub-directory?

[chrisdickinson]

(Also, this is excellent work! Thank you for PR'ing it.)

[benjamingr]

Sure, I'll address the comments tomorrow or later tonight. I'm fine with renaming to examples.