API: Add implementation for the scylla release version
API: Add implementation for the scylla release version

This adds the implementation to the scylla release version API.

After this patch a call to:

curl -X GET "http://localhost:10000/storage_service/scylla_release_version"

Will return the current scylla release version.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@scylladb.com>

kjniemi/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,raphaelsc/scylla,avikivity/scylla,raphaelsc/scylla,scylladb/scylla,scylladb/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,raphaelsc/scylla,kjniemi/scylla,kjniemi/scylla,avikivity/scylla