bioutils translate_cds does not correctly translate all human codons

[bsgiles73]

The Human Mitochondrial codon table includes the alternate initiator codon ATT. The correct translation of the first three codons in MT-ND2 should be MNP. But the translate_cds method in the sequences module does not return the correct translation.

>>> from bioutils.sequences import translate_cds
>>> from bioutils.sequences import TranslationTable
>>> translate_cds("ATTAATCCC",translation_table=TranslationTable.vertebrate_mitochondrial)
'INP'

According to the NCBI translation table, ATT encodes for both Methionine and Isoleucine. If the codon is the first codon of the coding gene it should be a M, else it is a I. These alternate initiator codons are species specific. For human there is ATT, for mouse ATC, and for Coturnix, Gallus GTG.

The translate_cds method should enable users to pass in enough information that the method can return the correct amino acid if the first codon is included and the species matches.