Datastax DSE and OpsCenter images point to a bucket that doesn't exist

[wjglerum]

The images used to display the icons for datastax-dse and datastax-ops in the DC/OS UI are pointing to a bucket that doesn't exists.

For example:

• DSE: https://github.com/mesosphere/universe/blob/version-3.x/repo/packages/D/datastax-dse/500/resource.json#L16-L20
• OpsCenter: https://github.com/mesosphere/universe/blob/version-3.x/repo/packages/D/datastax-ops/500/resource.json#L16-L20

[vibhujain]

Thanks for pointing that out @wjglerum
WIP PR: #2321