Fix language dashboard display to trap `kalite_nphrases` key exception if it does not exist when languages are not yet processed.
Make the "Language Code" cell a link if language pack for the version and language code is available so user can download the language pack.
Wrap code in exception handler to capture IOErrors when opening the files.
Merge pull request #214 from mrpau/hotfix/212-exception-on-languages-dashboard

Fix language dashboard display to trap `kalite_nphrases` key exception i...