travis.yml update pandas to 0.18.0rc1
travis.yml update pandas to 0.18.0rc1

mrocklin/distributed,amosonn/distributed,dask/distributed,mrocklin/distributed,broxtronix/distributed,blaze/distributed,mrocklin/distributed,amosonn/distributed,dask/distributed,blaze/distributed,dask/distributed,amosonn/distributed,broxtronix/distributed,broxtronix/distributed,dask/distributed