Eliminate Retry (Mailings Have One Live Job), Modify Recipient Uniqueness Test to Use Job, Mailing Report Fixes

This issue covers several improvements to mail processing and the mailing report:

1. Eliminate Retry functionality:
1.1 Remove retry code
1.2 Remove Retry link from report
1.3 Each mailing now should have only 1 live job (is_test = 0). Mailings may still have many "test" jobs. If a mailing has multiple live jobs - this is an error condition.

2. Modify Recipient Uniqueness Criteria
Currently the rule to prevent sending the same mailing to a recipient multiple time is that the civicrm_email.id + mailing.id is unique. Modify this rule to use civicrm_email.id + mailing_job.id. This will fix the problem where recipients of a "test" job don't get the live mailing.

3. Include / Exclude Recipients of Mailings
These criteria should include or exclude contacts based on "targeted" recipients of the selected mailing(s) - NOT based on actual delivery status. This MAY be the current behavior - if so, leave as is.

4. Only Show LIVE Job in Mailing Report Delivery Summary
4.1 Delivery summary should ONLY show stats for the mailing's live job (and there will only be one). Test jobs are ignored.
4.2 Eliminate report logic for displaying multiple job stats in a table in the Delivery Summary section.

5. Rename the existing Resend action to "Re-use"
This function is basically a copy and re-use - so renaming it should help both us and the users be clearer about what it does (creates a copy of an existing mailing - w/ the same target recipients and content, and allows user to modify and send).