Resolve condition and error if token is manually deleted

[jonespm]

If the user deletes their access token in their account, the tool displays this error. There is no way for the user to resolve this immediately. They would either need to wait until the access token expires in one hour which would re-prompt them or put in a ticket and have us reset the tool.

This case probably should be caught and the user presented with a page to re-authorize.

To reproduce, launch the tool and authorize. Then go to Account->Settings, look for the integration called "Instructor Tools" or similar and delete it.

[jonespm]

This is a duplicate of #249