Create a Inbound Parse data parser

[thinkingserious]

A consumer and parser for the SendGrid Inbound Parse Webhook.

Acceptance Criteria:

• Implement all the functions here.

Reference:

• https://github.com/sendgrid/sendgrid-python/blob/master/sendgrid/helpers/inbound/parse.py
• https://sendgrid.com/docs/Classroom/Basics/Inbound_Parse_Webhook/setting_up_the_inbound_parse_webhook.html
• https://sendgrid.com/docs/API_Reference/Webhooks/parse.html