reduce space usage by storing half the objects

Resolves-bug: https://github.com/sebhtml/Ray-Cloud-Browser/issues/32
Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>
add code to generate binary index in format version 1

Resolves-bug: https://github.com/sebhtml/Ray-Cloud-Browser/issues/32
Signed-off-by: Sébastien Boisvert <sebastien.boisvert.3@ulaval.ca>