Version Bump v3.0.0: full v3 Web API support

Author: thinkingserious

sendgrid/helpers/mail/README.md

@@ -2,7 +2,7 @@
 
 # Quick Start
 
-Run the [example](https://github.com/sendgrid/sendgrid-python/tree/v3beta/examples/helpers/mail) (make sure you have set your environment variable to include your SENDGRID_API_KEY).
+Run the [example](https://github.com/sendgrid/sendgrid-python/tree/master/examples/helpers/mail) (make sure you have set your environment variable to include your SENDGRID_API_KEY).
 
 ```bash
 cp examples/helpers/mail_settings.py .
@@ -11,5 +11,5 @@ python mail_settings.py
 
 ## Usage
 
-- See the [examples](https://github.com/sendgrid/sendgrid-python/tree/v3beta/examples/helpers/mail) for complete working examples.
+- See the [examples](https://github.com/sendgrid/sendgrid-python/tree/master/examples/helpers/mail) for complete working examples.
 - [Documentation](https://sendgrid.com/docs/API_Reference/Web_API_v3/Mail/overview.html)