addition2-to-KAZOO-2118
addition2-to-KAZOO-2118+
Merge pull request #291 from onnet/addition2-to-KAZOO-2118

addition2-to-KAZOO-2118: Awesome!
KAZOO-1856: supress warnings about templates
KAZOO-1856: remove cb_context access from cb_vmboxes
KAZOO-1856: clean up setting charset on email
KAZOO-1856: properly set the extension of the voicemail

Use either the media_type from the media doc, or the content_type from the
attachment, to get the extension for the attachment.
KAZOO-1856: remove warnings about unused vars