run: Add --bootstrap option

Consolidate the get_started.py scripts in ./run. There's
no real need of having such scripts inside each sub
directory, they're still here for historical reasons.

So now, executing

./run -t qemu --bootstrap

Has the exact same effect as

qemu/get_started.py

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>