References + Addition of Company Class

Added ref: Logic to Presentation, Data to Logic.

Added Company.vb to Logic Tier.
Corrected IInvoice to Invoice.
Tier Communication

Tiers are communicating, I am now looking into getting the required data
from the database. (Committing as i go).
Fixed namespace problem by taking added namespace from DataTier. Need to do the same to Threetier. Also changed code to use OleDbAdapters instead of SQLAdapters.