Added api endpoint and database changes

An API endpoint has been added that will call the gen_within_distance
function. Code has also been added to initialize the database for the
application.

Finally, the latitude and longitude parameters of various functions were
swapped.
Added front end

A front-end page was added containing a web form. The user can enter a
latitude, longitude, and distance, which will be passed to the
appropriate api endpoint. Results will be displayed in a table.

This implements #9 and #8.