add psutil to travis.yml
add psutil to travis.yml

marianotepper/dask,jayhetee/dask,hainm/dask,pombredanne/dask,clarkfitzg/dask,PhE/dask,cpcloud/dask,mikegraham/dask,jayhetee/dask,blaze/dask,mraspaud/dask,ssanderson/dask,blaze/dask,PhE/dask,ContinuumIO/dask,hainm/dask,esc/dask,simudream/dask,jakirkham/dask,simudream/dask,wiso/dask,jakirkham/dask,marianotepper/dask,freeman-lab/dask,minrk/dask,ContinuumIO/dask,gameduell/dask,jcrist/dask,cowlicks/dask,wiso/dask,chrisbarber/dask,dask/dask,pombredanne/dask,vikhyat/dask,minrk/dask,clarkfitzg/dask,freeman-lab/dask,vikhyat/dask,mrocklin/dask,dask/dask,mrocklin/dask,mraspaud/dask,jcrist/dask,esc/dask,ssanderson/dask