fixed/improved biosource validators for cell_line and tissue
fixed/improved biosource validators for cell_line and tissue

hms-dbmi/fourfront,4dn-dcic/fourfront,hms-dbmi/fourfront,hms-dbmi/fourfront,4dn-dcic/fourfront,4dn-dcic/fourfront,4dn-dcic/fourfront,hms-dbmi/fourfront,hms-dbmi/fourfront