Missing Bulk Email activity type causes activity selector to fail

Based on several forum reports, some sites are missing the 'Bulk Email' activity type. The queries to exclude Bulk Email activities for target and assignee contacts in the Activities selector currently fails when that activity type existing (see CRM/Activity/BAO/Activity.php getActivities() from line 758).

1. Modify getActivities to skip this clause if Bulk Email activity type is not found:

"AND {$activityTempTable}.activity_type_id <> {$bulkActivityTypeID"

2. Add a check for the existence of Bulk Email activity type to 3.4.6 upgrade - insert if not found (can re-use insert code from 3.0.alpha1.mysql.tpl)