Report percent identity regardless of assembly length

[tomkinsc]

Our pipeline currently has a gate to only consider assemblies successful if their length is greater than assembly_min_length_fraction_of_reference. In our metrics we report the assembly length (if it passes), but we do not report the assembly length as a fraction of the reference. It would be nice to report when it fails or succeeds, along with the fraction of unambiguous bases. This would help tune the parameter when re-running analyses that have failed.