Added a realtime price ticker that updates from tickerinfo.php with JS...

...Also fixed a typo in tickerinfo.php (didn't update schema).

Currently this code updates the <li>s in the "Ticker" dropdown but feel free to move those elements wherever, @jvanoel. All that is required is that there are elements on the page with the IDs "current-price", "market-cap", "total-supply", and "seconds-since-update".

Fixes #132
Feel free to reopen #132 if you want it to include making the ticker prettier.