Convert Abstract to Markdown w/ Formatting

Unlike HTML, Markdown will render as a preview of the file in the GitHub file browser ([for example](https://github.com/farmdawgnation/hyperloop/blob/97bfcf1b735122247e710c480cbb532b9601a6f8/1.%20Abstract/index.md)). Also, I made some minor improvements like putting a wrap on the text and linking the email addresses.