changed a lot of THINGS!!!
1. Changed CommandExecutor, added in the save function. now after every operation the file is saved.
2. modified LogicFacade to pass storage to commandexecutor for saving of the file
3. added some mutator and accessor in ModelTask to get date and times in a string format different from stringproperty format
4. modified modeltaskToSaveString class. Now the program can correctly save to the textfile
5. fixed bugs in storage.Now can save and load without problems :)
6. added 2 Junit tests for testing storage and TestModelTaskToString class.
changed EditListener to output the correct string
Merge remote-tracking branch 'origin/yongkai'
Merge remote-tracking branch 'origin/krystal'