refactor/fix(git-utils):add funcs to common/git
refactor/fix(git-utils):add funcs to common/git

Adds the (new) following functions:
    - git_commit()
    - git_add_all()
    - git_status()
    - git_head_commit()
    - git_tag()

checkmate/simpl,ziadsawalha/simpl,larsbutler/simpl,samstav/simpl,ryandub/simpl