OptMAGE only works with MG1655

[dbgoodman]

We don't pass in a genome FASTA to optMAGE, so it uses the default, U00096.2. To fix, we need to change the OptMAGEConfig() call to include a ref_genome_source_location kwargs as in https://github.com/churchlab/optmage/blob/master/src/optmage/oligo_designer.py#L101.