remote-helpers: trivial style fixes

In accordance with pep8.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-helpers: cleanup more global variables

They don't need to be specified if they are not going to be set.

Suggested-by: Dusty Phillips <dusty@linux.ca>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
remote-hg: support for notes

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