MMS: Fix lookup of vanity addresses

Avoid the use of the function PhoneNumberUtils.stripSeparators for non-strict
phone numbers.

Change-Id: I9db09780fd066f07fd0c22a8dad7431d34805b25
JIRA: CYAN-57
Issue: https://jira.cyanogenmod.org/browse/CYAN-57
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>