add feature to use the Tooling API

[mkreth]

Add a config to use to Salesforce Tooling API. Salesforce provides things like the SecurityHealthCheck Score, the SecurityHealthCheckRisks and the Object Limits only via the Tooling API. Restforce already comes with support for the Tooling API, a boolean config use_tooling_api can simply change between the Tooling API and the regular REST API.