Adding support to pass name on from_email

[wiltonsr]

Hello,

Thanks for Flask-Sendgrid extension.

it would be nice if we could enter the sender's name using the optional tuple format as seen here.

Because of this, I'm sending a PR that adds this possibility.

[coveralls]

Coverage decreased (-1.5%) to 98.529% when pulling d7f295f on wiltonsr:name-from-email into ee58813 on frankV:master.