Version Bump v5.4.1: Bug Fixes

Version Bump v5.4.0: Hacktoberfest Release

Version Bump v5.3.0: sendgrid#348: Allows users to submit rfc822 form…

…atted email addresses

Version Bump v5.2.1: Pull sendgrid#364: Install prism with non superu…

…ser account

Version Bump v5.2.0: sendgrid#335: Permit unicode string values with …

…Substitution helper

Version Bump v5.1.0: Pull sendgrid#338, Solves sendgrid#292 __str__

Version Bump v5.0.1: Pull sendgrid#337, fixes issue sendgrid#366: Val…

…ue Error

Version Bump v5.0.0: fixes sendgrid#328 and sendgrid#321

Version Bump v4.2.1: Issue sendgrid#321: Installing 4.2.0 installs th…

…e wrong version of python-http-client

Version Bump: v4.2.0: Pull sendgrid#318 Add ability to reset request …

…headers on client attribute