Link URI re: issue #486

The proposed changes address the silent failing of adding a link to an unrecognized URI. They allow the user to correct any potential mistakes made to the initial address through a prompt dialogue. 
How about if it's malformed and ```tryHttp``` is set, we search for a period, prepend ```http://``` if there is one, and otherwise return ```false```? So then this will just stop "asfsdgasga" from turning into a URI.