Some more baps_reader_spec refactoring.
Start using simplecov.
Forgot Gemfile.lock last time.
Move add_child and remove_child stubs.

These are going into ModelObject, as part of a drive to clean up the
ModelObject hierarchy.
Spec changes.

Mostly adding the spec_helpers, but some new tests have been added to improve
code coverage.
Model objects now have a can_have_children? method

move_to now checks this method before moving the object.

Also, the model object specs have been refactored a tad.
Swap around the arguments for PrivilegeSet methods

has? and require make more sense this way around, I think.

Also some changes to the specs and PrivilegeSet users to accommodate this.
More test coverage and related activities.