refactoring

refactoring resolvers a bit.
fixing some minor issues
adding metadata resolver
moving fits-test script artefacts to sub-dirs (#fixes 5)

the .output and .release dirs are now not hidden and moved created
under a new .bb-testing directory.
Each subsequent run of the script, checks if this directory exists and
removes it.
returning exitCode 125 if one of the input dirs is empty (code didn't run)