email usability enhancements

[jmartin-sul]

• it would be great if emails sent had project name in subject
• discovery report email subject should indicate number of objects and error count (or at least whether or not there were errors)
• it would be great if preassembly job email subject had number of successful and number of failed objects in subject

feel free to break into smaller tickets if its easier to just implement one part at a time.

[atz]

Maybe a few too many things to pack into the subject line.

[atz]

Box 1 checked by #368

[jmartin-sul]

fine to present discovery report summary info in email body.

fine to just put table contents in email for discovery report.

might want to have some sort of cut off where we only present summary data for discovery reports over a certain size, since the reports can be huge.

we won't be able to do this sort of thing for pre-assembly without tweaking the way it runs, since we don't collect reduced summary data on that, and we don't want to re-parse all the output everytime we want to send an email or display something. so pre-assembly email will probably be less informative than discovery report.

[peetucket]

Closed in favor of #976