Storing category in a separate textfile
Include list_categories.json in .gitignore
Integrating category storage with ReaderWriter, TaskManager, Controller, and ICommands
Modify TaskManager to use ObservableList
Merge pull request #109 from mikelimantara/working

Use ObservableList
Merge remote-tracking branch 'upstream/observablelist' into working
Show ControlsFX Dialog when error to load files