Refactor Transfer + Convention

In this PR:
 - transfer.js has almost been completely re-written to reduce the number of bugs and user warnings.  These changes include
    - Better currency + cashbox selection
    - Reducing global variables to $scope and dependencies
    - Using html5 validation + ng-submit for blank fields
 - English and French translations pruned, reduced unused keys
 - transfer.html + convention.html better ng-show/if bindings, reduce clutter
 - convention.html currency dropdown now appears on the screen
 - Many small syntax fixes