cdr/cdr_csv.c: Add a new option to enable columns added in Asterisk 1.8

This patch adds a new option to cdr.conf, 'newcdrcolumns', that will handle CDR
columns added in Asterisk 1.8. The columns are:
 * peeraccount
 * linkedid
 * sequence
When enabled, the columns in the database entry will be populated with the data
from the CDR.

ASTERISK-24976 #close

Change-Id: I51a57063f4ae5e194a9d933a8df45dc8a4534f0b