Add repo_id to metadata.yaml

[JRWallace]

We realized there might be an issue with mapping qc file names/metrics back to the metadata table in a way that imposes 1:1 relationships between a given sample and its metrics. For example, if two PIs are running RNAseq experiments and the sample prefix is 'Control_1' for both projects, we don't have a way to know which 'Control_1' a given fastqc.zip file is referencing. To try to account for this, we are adding a 'repo_id' field to metadata.yaml since this should help us distinguish which 'Control_1' sample is which.