Pip is used by this task, make sure ensure-pip is used so it is
present.
While here, install git-review to a venv and symlink it globally to
keep things separate.
Change-Id: If6b1abd2545c68f727bddc5317797236f451b67c
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>
Signed-off-by: Ian Wienand <iwienand@redhat.com>