modified SearchHandler and SearchParser to implement Search function.
Merge branch 'master' of https://github.com/cs2103aug2014-T13-2J/main

# By Nee Si Yao
# Via Nee Si Yao
* 'master' of https://github.com/cs2103aug2014-T13-2J/main:
  Fix Delete function - can delete single/multiple tasks. Add deleteTask() in Storage.
  Remove Storage.getInstance() from AddHandler.