Added optional configs for settings

This allows the following settings variables to be set:

 - `TASTYPIE_SWAGGER_APP_NAME` configures the display name on the documentation page. Defaults to `swagger`.
 - `TASTYPIE_SWAGGER_APP_NAME` configures the app link on the documentation page. Defaults to `/`.
 - `TASTYPIE_SWAGGER_SHOW_DEV` allows showing or hiding the development links. Defaults to `False`.
 - `TASTYPIE_SWAGGER_KEY_NAME` allows configuring the api key name. Defaults to `apiKey`.
 - `TASTYPIE_SWAGGER_API_KEY` allows configuring a prefilled api key. Defaults to an empty string.