ignore fixture_md5 table when creating dbix resultset files
modify crispr off targets table column chr_id to chromosome and store chromosome as text field
remove crispr off targets chromosome validation, allow for scaffolding and other strange chromosome names
add test for crispr off target chromosome values, fix current tests which refered to the old column name
db migration 32, change chr_id column on crispr_off_targets table to chromsome, just a text field holding the chromosome name