clinseq-converge-stats update

Add a new file to the converge stats command, this is the Stats.tsv from summarizing SNVIndelReports. To help accomplish this make base quality and mapping quality a parameter of Base.pm under Converge.
If you include this list as a separate attribute of `stats` like this:
```perl
valid_values => [qw(all wgs_snv_summary exome_snv_summary
wgs_exome_snv_summary rnaseq_tumor_cufflinks_isoforms
rnaseq_tumor_cufflinks_isforms_merged snv_indel_report_stats
rnaseq_tumor_cufflinks_genes)],
```
then UR will validate the supplied value, and the list will appear in the documentation in a standard way.