Modify search and filter command
Remove extra fields
Add more param to update command
Separated task modifier into a separate class
Remove unused imports and constant
Merge branch 'xy-search-command' of github.com:cs2103aug2014-w13-4j/main into pn-logic
Search method in logic
Correct comment
fix bug in complete task
Add test for complete task with date
Merge branch 'pn-logic' of github.com:cs2103aug2014-w13-4j/main into pn-modify-chuyu-storage