Add show action to the api v1 for problems

This allows a problem id to be passed to the problem api and only
information for that problem will be returned.
Add a problems err and notices in api show action
Adding file not found handling

If there is no problem for the requested id the api will now correctly
return a 404 status.
Limit the show action to just the problem

This commit backs out the nesting of the error and notices as this would
be better placed in an error or notices route.
Merge pull request #693 from CallumD/add_notices_to_show_action

Add notices to show action