Rename release packages and compress the tarball
Move release packages to /releases subdirectory
Add rudimentary index page for /releases/

including links to source releases.  This assumes that Git tags are
created for each release (openseadragon/openseadragon#74) and named with
the convention "v<version>".
Fix wording in Download section
Merge pull request #15 from bgilbert/dist

Update site for packaging changes