Add simple method to allow newsletters to be forwarded

[saltybeagle]

Create a utility to forward the email newsletter a user is reading to another user.

This can be handled two ways, either providing a consistent link within the footer as simple as:
<a href="mailto:?subject=Check+out+this+newsletter&amp;body=http://example.com/blah">Send to a friend</a>

Or something more complicated where the fully preserved email is sent to a provided email address.