add metadataStub.js to represent metadata , eventually will be replaced with information retrieved from server
add metadataStub.js to represent metadata , eventually will be replaced with information retrieved from server

ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,ucscXena/ucsc-xena-client,acthp/ucsc-xena-client,ucscXena/ucsc-xena-client,acthp/ucsc-xena-client,acthp/ucsc-xena-client