Remove the complexity of DB schema.

	1. Combine Department and Business by removing all business-related
tables.
	2. Combine Community and Group by removing (in previous CL)
	3. Combine Bulletin and PrivateMsg by removing all Bulletin and
PrivateMsg related table and add the following tables
		a. Message
		b. Recipient
		c. NoticeConfirm

Add two columns, Name and Description, into table AddressBook