views: introduce endpoints /bounds, /around

/bounds/?nw=xxxx,xxxx?se=xxxx,xxxx is a new endpoint for specifying a
bounding box, points inside which should be returned.

/around/?center=xxxx,xxxx?radius=xxxx is a new endpoint for specifying
a circular area, points inside which should be returned.

This is currently untested.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>