Create andy_dataset.md

Q&A for beginning to work with DC 2013 Crime dataset.
Update andy_dataset.md

Answered fifth question.
Update andy_dataset.md
Adding Daniel's dataset research
Merge pull request #50 from andy-vee/master

Dataset preliminaries assignment - Andy Vance
Merge pull request #51 from daniel-chung/master

Adding Daniel's dataset research
Added draft of brian.md