project export contains unrelated bookmarks

[wlhunt]

It appears that the --all-references-bookmarks does not respect the pid supplied.
So this command line:
$ python slycat-dump.py --all-references-bookmarks --project-id 123 output_dir
should write bookmarks only from pid 123

or

Implement a new arg that exports the bookmarks and references as well, like this:

$ python slycat-dump.py --include-bookmarks --project-id 123 output_dir