Maintain a mapping of the DID that owns each database

[tahpot]

We need to add the following endpoints to the storage-node API:

• databases() - Allow a DID to fetch a list of all databases they own
• databaseInfo(dbName) - Fetch information about a database. This information should include; human readable name, permissions, number of records, total database size

The following information needs to be stored for each database when it is created or it's permissions updated:

• human readable name
• permissions

Once implemented it will enable a path to the following technical capabilities:

• In client-ts fetch full database permissions for any databases you control (ie: list of read/write DID's -- they are currently obfuscated)
• Enable payment based on resource utilization
• Modify database permissions (read, write, delete) rather than overriding them every time.
• Synconrizing all databases owned by a particular DID
• Deleting all databases owned by a particular DID

[tahpot]

This is now complete and included in #14