thrift: partially implement batch_mutate()
thrift: partially implement batch_mutate()

Only mutate case (not deletion) for ordinary columns.

duarten/scylla,acbellini/scylla,kjniemi/scylla,asias/scylla,rentongzhang/scylla,stamhe/scylla,dwdm/scylla,avikivity/scylla,respu/scylla,senseb/scylla,shaunstanislaus/scylla,rentongzhang/scylla,acbellini/scylla,eklitzke/scylla,aruanruan/scylla,bowlofstew/scylla,rluta/scylla,linearregression/scylla,senseb/scylla,phonkee/scylla,victorbriz/scylla,tempbottle/scylla,guiquanz/scylla,tempbottle/scylla,linearregression/scylla,shaunstanislaus/scylla,capturePointer/scylla,phonkee/scylla,bowlofstew/scylla,scylladb/scylla,scylladb/scylla,guiquanz/scylla,linearregression/scylla,glommer/scylla,wildinto/scylla,kjniemi/scylla,senseb/scylla,kangkot/scylla,wildinto/scylla,kangkot/scylla,scylladb/scylla,justintung/scylla,stamhe/scylla,avikivity/scylla,capturePointer/scylla,dwdm/scylla,bowlofstew/scylla,gwicke/scylla,victorbriz/scylla,kangkot/scylla,raphaelsc/scylla,eklitzke/scylla,justintung/scylla,rluta/scylla,asias/scylla,respu/scylla,rentongzhang/scylla,victorbriz/scylla,eklitzke/scylla,tempbottle/scylla,justintung/scylla,stamhe/scylla,glommer/scylla,wildinto/scylla,raphaelsc/scylla,shaunstanislaus/scylla,glommer/scylla,phonkee/scylla,asias/scylla,avikivity/scylla,scylladb/scylla,rluta/scylla,dwdm/scylla,gwicke/scylla,aruanruan/scylla,acbellini/scylla,gwicke/scylla,respu/scylla,kjniemi/scylla,aruanruan/scylla,raphaelsc/scylla,duarten/scylla,guiquanz/scylla,capturePointer/scylla,duarten/scylla