cockroachdb/cockroach

Planned improvements to the CLI of CockroachDB, including but not limited to cockroach sql.

Issue title prefixes:

• cli/conn: code that establishes a client-server connection (common to multiple commands)
• cli/tables: code that presents tabular results (common to multiple commands)
• cli/config: command-line flag handling + client-side configuration
• cli/XXX: command-specific issues for cockroach XXX