Gemfile.lock updates for 0.3.1
wipe all db collections (aside from system) when running tests
ignore textmate files
Add bson_ext to dev depenencies
Import code from learnup
Rename project from Sluggable => LearnupSluggable
add simplecov for code coverage
Add debugger to dev gemfile group
enable code coverage with COVERAGE=1 rspec ...
get 100% code coverage
Add more specs around scoping
* Regenerate slugs every time the target field changes
  * Change to callback => [:before_validation, { :on => :create }] (or :before_validation_on_create)
    if you'd only like the slug generated once
  * Otherwise, old_slugs will be put in the old_slug array and a MongoMapper::DocumentError will
    be raised with the old + new slug information (useful for redirecting clients)