Email currently registered about refund policy

[nathenharvey]

• No refunds after 6/5
• Many on the waitlist, no hard feelings if you can't make it

[nathenharvey]

https://manage.busyconf.com/events/devopsdaysdc2015/messages/5568b087c78cf80400000064/edit

I've asked @gallimorej to review and send if it looks good.

[gallimorej]

Sent on 5/29.