Fix an issue with rose-ana where it believes files in the app's file directory are tests

If a developer puts files inside a rose-ana app's file/ directory (potentially a sensible thing to do with KGO), rose-ana treats the resulting additions to the config object (file:......) as tests and tries to process them. We need to exclude these in the same way we exclude "env". 

There's an outside chance someone will put:

[file:hello]
comparison=Exact
extract=.....

but that would be an unlikely name for a test - I'd encourage people not to use colons in that place unless they mean them!