Create FileWatcher

Uses Java 7 NIO watching API.
Add history command
Add watch command for testing purposes
Test watch task with auto committing
Provide OSX specific FileWatcher implementation
Make FileWatcher API use java.io.File
Make FileWatcher API use java.io.File
Code style
Block until FileWatcher actually registered itself
Add FileWatcherSpec
Deactivate OSXFileWatcher for now
Organize imports
Add AggregatingActor
Code style
Use AggregatingActor in watch command
Create RepositoryActor

So far handles file watcher events and auto commits.
Merge branch 'feature/filewatcher' into develop