Remove broken HTML from asset request text
Remove unused font request variable in submit processing
Save submitted email address to post meta and display when needed

We were capturing this only for the title previously, which doesn't help much.
Send a notification email to the requestor when an asset request has been received.
Prep and unprep mail filters when the plugin sends notifications

This allows us to set a mail from and a mail from name that is more expected than the default WordPress sender.