Bash script

@westonruter What do you think ?
I've did some steps ( in https://github.com/x-team/wp-upgrader/commit/ed2f60578b689648f36423cc8736399730572815 )  based on the fact that the site root is versioned with git, but i think i might need to actually detect if it is a git repo, and if not, create one, so we can roll back.
Will be checking while i checkout the repo and follow the build flow tomorrow.
Cheers!