Object#ip_sub is now deterministic

Concerns #1

Some other minor changes:
  * Added yard doc and redcardpet as dev dependencies
  * Rearranged file structure
  * #ip_merge and #ip_sub are no longer monkey patched into Kernel
    (They are now in a seperate module that gets mixed into Object)
  * Added some specs and docs
  * Bumped version to 0.0.2, should not break compatibility