add update_from_file & edit_def commands to /apps/APP and /apps/APP/vms/VM

[ryran]

The update_from_file cmd will take a file argument and if it loads as proper json content with the skeleton of an app or vm, it will be passed to the appropriate API call to update said app or vm.

The edit_def cmd will retrieve the design aspect of the APP or VM and save it to a tempfile and then open up that with a text editor -- in order: $RAVSH_EDITOR, $EDITOR, gvim, vim, vi. After the subprocess has finished, it will essentially call update_from_file against the file.

[ryran]

Tracking in #128