Added Date
Refactored output javadoc
Added parser to parse from string to a date object.
Refer to https://docs.google.com/spreadsheets/d/1A_enIhjFT220EPobggQ3lZ3hyz3evQ9SVA_b3iCm2ko/edit#gid=0
for the list of acceptable date formats

#40
Merge branch 'master' into parser/Victor
Executable
Output for Help
Added output for Exit
Changes in method flow, variable names
Merge branch 'master' into controller/sharon
A lot of changes
Output message for Errors
Merge remote-tracking branch 'origin/ui/victor' into controller/sharon
Added message field to Command Class
Merge branch 'ui/victor' into parser/Victor
Complete HelpHandler
Output for Undo
#61
Merge remote-tracking branch 'origin/parser/Victor' into controller/sharon
Merge remote-tracking branch 'origin/ui/victor' into controller/sharon
Changed numbering to use brackets instead of dots.

From
1. <Task Name>
2. <Task Name>

To
[1] <Task Name>
[2] <Task Name>

#56
Removed Exception from `displayResult(Result result);`