Tentative parser seems to work

In this format
<command word> <task description> : <Start> - <end> , <Start> - <end>
....
modified the timeservice class. and make changes to other files affected by this change. added testparser unit test again
Merge remote-tracking branch 'origin/master' into yongkai
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/parser/TentativeParser.java
deconflict

deconflict
Added Tentative logic.
Currently has null pointer exception @ TimePeriod.convertStartDate
Merge branch 'master' of https://github.com/cs2103aug2014-t11-1j/main into krystal
Null pointer exception should be fixed. Initilised the strings to null.