adding sendgrid sender

Author: paganotoni

README.md

@@ -0,0 +1,29 @@
+### Sendgrid Buffalo Sender
+
+This is a [buffalo](github.com/gobuffalo/buffalo) sender for the [Sendgrid](https://https://sendgrid.com//) email service.
+
+#### How to use
+
+In your `mailers.go`
+
+```
+import (
+    ... 
+    ssender "github.com/paganotoni/sendgrid-sender"
+)
+
+var sender mail.Sender
+var hcomposer hermes.Hermes
+
+func init() {
+	serverToken := envy.Get("Sendgrid_SERVER_TOKEN", "")
+	accountToken := envy.Get("Sendgrid_ACCOUNT_TOKEN", "")
+	sender = ssender.NewSendgridSender(serverToken, accountToken, false)
+}
+```
+
+And then in your mailers you would do the same `sender.Send(m)` as this sender matches buffalos [`mail.Sender`](https://github.com/gobuffalo/buffalo/blob/master/mail/mail.go#L4) interface.
+
+#### Test mode
+
+Whenever the GO_ENV variable is set to be `test` this sender will use [mocksmtp](https://github.com/stanislas-m/mocksmtp) sender to send messages, you can read values in your tests within the property `TestSender` of the SendgridSender.