Bug when user has insufficient permissions.

Reported by @mark-up (Unfuddle)

In NinjaXplorer, if the user doesn't have write permissions, the file can not be viewed. This is incorrect behaviour.

The user should be able to view the file, but not edit it.

See video: http://screencast.com/t/oFjYet6nbw7

Reference:
https://ninjagroup.unfuddle.com/a#/projects/38481/tickets/by_number/46?cycle=true
