Added a test XML for the Jukes-Cantor model.
Added a test XML for the Jukes-Cantor model.

Anaphory/beast2,tgvaughan/beast2,CompEvol/beast2,Anaphory/beast2,CompEvol/beast2,Anaphory/beast2,tgvaughan/beast2,Anaphory/beast2,tgvaughan/beast2,CompEvol/beast2,tgvaughan/beast2,CompEvol/beast2