Get a few frames to warm up
Get a few frames to warm up

It's strange, but it seems that the first frames we get are broken in
some cameras. Get a few more to make sure things will work.

Signed-off-by: Claudio Matsuoka <ef7f691d9947ca9adbfeb1538a53a661ec9f041b@gmail.com>

cmatsuoka/framegrab,cmatsuoka/framegrab