add memory spec
add memory spec

thomasmaurel/ensj-healthcheck,Ensembl/ensj-healthcheck,Ensembl/ensj-healthcheck,thomasmaurel/ensj-healthcheck,thomasmaurel/ensj-healthcheck,Ensembl/ensj-healthcheck,thomasmaurel/ensj-healthcheck,Ensembl/ensj-healthcheck