Ignore importerror when defining RandomState.choice
Ignore importerror when defining RandomState.choice

Fixes #766

blaze/dask,vikhyat/dask,pombredanne/dask,chrisbarber/dask,dask/dask,blaze/dask,pombredanne/dask,mrocklin/dask,mraspaud/dask,cowlicks/dask,jakirkham/dask,jakirkham/dask,ContinuumIO/dask,jcrist/dask,ContinuumIO/dask,mikegraham/dask,cpcloud/dask,mraspaud/dask,vikhyat/dask,gameduell/dask,dask/dask,mrocklin/dask,jcrist/dask