Add Eric Hughes as author to crypto glossary
add Hal Finney's Detecting Double Spending
Merge pull request #54 from NakamotoInstitute/detecting-double-spending

add Hal Finney's Detecting Double Spending
fix indents
Clean up TTP HTML
Merge pull request #55 from NakamotoInstitute/trusted-third-parties

Clean up TTP HTML
Merge pull request #57 from NakamotoInstitute/master

pulling master in