[build/onie installer] Install grub for SONiC post migration from another NOS#949

Merged

lguohan merged 2 commits intosonic-net:masterfrom padmanarayana:sonic_grub_install

Sep 17, 2017

+121-5

Commits on Sep 9, 2017

Install grub for SONiC post migration from another NOS
padmanarayana
committed

Commits on Sep 15, 2017

Install grub from bundled debian package instead of using ONIE's. Address review comments
padmanarayana
committed