Start metadata-storage in reva

[IljaN]

No description provided.

[butonic]

this appends metadata to the default path, which is

• Reva.Storages.Common.Root: /var/tmp/ocis/root for ocis
• Reva.Storages.EOS.Root: /eos/dockertest/reva
• Reva.Storages.Local.Root: /var/tmp/reva/root
• Reva.Storages.OwnCloud.Root: /var/tmp/reva/data

ultimately, I would like to use the common config for as many drivers as possible. Anyway, the root for metadata might be very different from the root for user data, and making it a subfolder might even conflict with other storage providers.

To really give the metadata driver its own root we need to parse the flag:

		&cli.StringFlag{
			Name:        "storage-metadata-root",
			Value:       "/var/tmp/ocis/metadata",
			Usage:       "the path to the metadata storage root",
			EnvVars:     []string{"REVA_STORAGE_METADATA_ROOT"},
			Destination: &cfg.Reva.Storages.Common.Root,
		},

This would then be used as the EOS driver root, the local driver root, the owncloud driver root or the ocis driver root.

I would use the reva-storage-metadata command as a blueprint for a reva-storage-home and reva-storage-users command, that would replace the existing commands and to combine them with the separate data provider commands. but that is a subsequent PR.