Created check for valid CSV file.
More complex matching for email and phone implemented.  Output CSV created.

Now matches both email/phone columns (with room to expand to more columns).  If either value has been used, the ID is matched to original person.  New CSV also written after matching is done.
Modularized code and changed matching algorithm slightly.

Code is now refactored into smaller methods that are shared between check_email and check_phone methods.  All phones/emails with common numbers now match to the original phone/email.  For example, if customer A has Email1, Email2 and customer 2 has Email2, Email3, then Email1, Email2, and Email3 will all correspond to the same CustomerID.
Added instructions and made slight formatting changes to solutions.rb