Added currentstatus query.

<host>/currentstatus returns the current status of all stocks in the
S&P500 (ask, bid, and last). <host>/currentstatus?select=ask returns
just the ask prices of the stocks, and similarly
<host>/currentstatus?select=bid returns the bid prices.
Created allhistories query

<host>/allhistories returns a JSON object where keys are times, values are
objects for each of the 500 securities containing the ask, bid, and last
prices for each security. By default, returns the last 12 ticks.

allhistories?n=N returns the last N ticks.

allhistories?select=ask only lists ask price for the security (and
similarly for bid and last).