db_tool: check return value from controller->run()

- If the controller returns an error object, dump it to the screen,
  along with instructions to run the script with '--help'
DBTool: issue #166; remove connecting to database check

- Moved database `connect()` check into the `BUILD` method for
  _idGamesDB_, so that code block in _DBTool_ is no longer needed
- Return an _Error_ object if no output option was used on the command
  line
idGamesDB: close #166; move connect() call into BUILD
DBTool: return an error if asked to process an unknown file
renamed: Views/CLI/idGamesDbDump.pm -> View/idGamesDBDumpCLI.pm
View/GenericCLI: issue #176; added a generic "View" object
renamed: dump_o_matic.md -> callbacks.md
callbacks.md: updated title of document
View/GenericCLI: fixed package name
db_tool: issue #176; moved "banner" below where view is created
DBTool: Check config/view attributes in BUILD()

- Added call to view object in `request_update()` callback
Roles/DatabaseSchema: add log level to request_update() callback
docs/callbacks: changed DBTool references to "Model"
callbacks.md: added more methods to the View