README: Remove ubuntu build instructions
README: Remove ubuntu build instructions

Scylla needs thrift and antlr3 which are not provided by ubuntu. We need
to compile them from source in order to build scylla. For now, let's
only support build on Fedora.

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