HR-200 FIX

this fix involves following : 

- creation of 'Visa Expiration' activity type.
- assigning this activity type to appropriate contacts (linked contacts using target_contact_id for activity) using <code> CRM_HRVisa_Activity::sync </code> function.
- creating a weekly schedule reminder for Visa Expiration activities whose status is 'Scheduled' .

Also handled upgrade for it.