Adding output option for itemized Form 8949 reporting

When reporting your bitcoin taxes, you'll probably have to submit an itemized record of each transaction on your Form 8949 (http://www.irs.gov/pub/irs-pdf/f8949.pdf) which accompanies your Schedule D reporting of capital gains. 

While the currency calculator accurately reports your total gains/losses per year, it did not output the results in an itemized format that could be entered in the f8949. 

This pull request adds an option for outputting the itemized transactions for 8949 reporting. 

You can try it out at http://tkriplean.github.io/crypto-currency-calculator/ first if you wish.

p.s. one minor limitation is that the itemized results aren't strongly broken out by year as the summarized gains/losses are.