debian/control: Make mongodb arch all, instead of arch-specific.

The package mongodb is only a metapackage intended to pull in other packages
and it has absolutely zero architecture-specific content.

Signed-off-by: Rogério Brito <rbrito@ime.usp.br>
gitignore: Ignore quilt's state directory.

Signed-off-by: Rogério Brito <rbrito@ime.usp.br>