essentials in one list and put to profile page

1. Added items "essentials" to ItemManager class.
2. Put all "essentials" Items into one list "essentialItems"
3. Wrote a new function retrieveEssentialItems() to retrieve essential
items from ItemManager
4. Used retrieveEssentialItems() in profile to get user's essential list
to display on profile page
Merge remote-tracking branch 'origin/master'

Conflicts:
	nbproject/private/private.xml
	web/profile.jsp