Add ability to configure registry for snapshots for each workspace

[mmorhun]

For now, registry, in which all snapshots of all workspaces is stored, defined in Codenvy system properties. We need to allow to a user configure this parameter per workspace (UI issue for this is here). When a user do not configure this parameter for a workspace, value from Codenvy system properties will be used as default.

[bmicklea]

No need for UI - this can be addressed through configuration files.

[garagatyi]

We will address this through configuration files instead of on a per-workspace basis.