Workspace and installation properties

In order to support installation time settings that survive across different workspaces, there are now two Properties instances:

- workspaceProperties that persists configs specific only to one workspace. Example usage: save last date of succesfull update.
- installationProperties that persist configs visible to all workspaces. Example usage: save uninstall date. Its file will be ping ponged just like the survey. The installationProperties will only be written to at install time.