Implement MyMongoid Lifecycle Callbacks
Implement define_callbacks
Implement Callback Class
Implement CallbackChain
Implement set_callback
Implement run_callbacks
Implement Around & After Callbacks
Remove unused code: sort_callbacks
Implement Callback#compile
Implement Compile Before Callbacks
Implement Memoize Compilation
Implement Compile Around Callbacks
Implement Compile After Callbacks
Execute run_callbacks with compiled callbacks
Merge pull request #7 from puiesabu/W3-callbacks

Week 3 exercise: callbacks