Updated relation tests to catch new bug
Fixes a bug when clones are passed into `Spine.Model::load()`
Collection::add() and Collection::remove() methods
Merge pull request #440 from adambiggs/relation-load-bug

Found a bug when passing record clones into Spine.Model::load()
Merge pull request #441 from adambiggs/add-remove-relations

Collection::add() and Collection::remove() methods
text editor removed some whitespace
Added tests for client-side UUIDs