add grep config
add grep config

* configure ack-like output with `git g`
* enable regex support

OctavianRotari/dotfiles,paulhirschi/dotfiles,zhenglaizhang/dotfiles-1,pekosi/dotfiles,abhisood/dotfiles,joeandrews/dotfiles,ptgamr/dotfiles,jacobxk/dotfiles-1,fieteboerner/dotfiles,pekosi/dotfiles,damca/dotfiles-ubuntu,patnolanireland/dotfiles,Boukefalos/dotfiles,nicknisi/dotfiles,Jooho/dotfiles_mac,NerdPad/dotfiles,patnolanireland/dotfiles,fieteboerner/dotfiles,ptgamr/dotfiles,jbargu/dotfiles,OctavianRotari/dotfiles,Jooho/dotfiles_mac,zhenglaizhang/dotfiles-1,gblock0/dotfiles_unstable,jbargu/dotfiles,Reesi82/dotfiles,dyong0/dotfiles,nicknisi/dotfiles,neutrinog/dotfiles,bbtb1982/dotfiles,damca/dotfiles-ubuntu,bbtb1982/dotfiles,fieteboerner/dotfiles,nicknisi/dotfiles,jacobxk/dotfiles-1,SlyDen/dotfiles