Feature/983 data importer

# Warning

# Info

The release includes the new NPSP Data Importer, which helps you easily import your data into the Nonprofit Starter Pack

# Issues

Fixes #983 
Fixes #1020 
Fixes #1015 
Fixes #1014 


In fact I am.  matchExistingContacts() will create new contacts and add them to the mapping array with all their keys.  So dups within a batch get caught.  I have tests for this.