Remove sendgrid_api_key dependency from Settings

[verisadmin]

• I am working on this library . And I was thinking of using your libray for SendGrid, But you have a strong dependency of mentioning Send_Grid_API in settings.

• If you can make it possible that user can either mention api_key in settings or pass it as function argument too (If you think its feasible and makes sense).

• Why Remove Settings dependency ?

  • So that user can use as many service as he wants by simple passing the key in Function and let function do the rest of work.