remove toolz dependency from core
remove toolz dependency from core

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