configures any models defined in the application's configuration file. this method is automatically called
by the constructor.
an application normally contains a default model, which is specified in the "model" section of the application's
configuration file. additional model definitions can be specified in the configuration file by adding sections
whose name is in the form of "model_x" where x is some unique identifier.
valid configuration values for a model definition include "id", "datasource", "definition_module" and "debug".
The "datasource" attribute is mandatory for all model definitions; "definition_module" and "id" are mandatory for
all definitions other than the default, and all other attributes are optional for all model definitions.
when each model is loaded, a database connection will be made and all registered data types will be configured,
either manually or automatically using database reflection. Additionally the default context for each model
definition will be registered in Fins.DataSources using the value of its "id" attribute as the key.
in addition to being available from Fins.Model, the default model is also available from Fins.Datasources by its
"id" attribute, or if no "id" is specified, using the key Fins.Model.DEFAULT_MODEL , or "_default".