fix: timestamp in contactMethod is not updated

This commit fix value of startTimeStamp in Call.cpp when a new
contactMethod is created. It fix two problems:
-filter rows in SmartView
-update contactMethod lastUsedTime

Tuleap: #1585
Change-Id: I6f03db26e844531ee6954c835e43d19f24e16633
Reviewed-by: Nicolas Jäger <nicolas.jager@savoirfairelinux.com>