remote-bzr: tell bazaar to be quiet

Otherwise we get notification, progress bars, and what not.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-bzr: strip extra newline

It's added by fast-export, the user didn't type it.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-bzr: use proper push method

Not just randomly synchronize the revisions with no checks at all. This
is the way bazaar's UI does it.

Also, add a non-ff check.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>