add cython to travis.yml for bleeding edge bcolz
add cython to travis.yml for bleeding edge bcolz

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