v2.0.0

Merge pull request #3 from byng-systems/upgrade-to-sendgrid-5

Upgrade sendgrid/sendgrid to 5, remove Unirest, update base code

v1.0.2

Merge pull request #2 from eduardoconceicao/unsubscribe-email

Added unsubscribe functionality

v1.0.1

Merge branch 'development'