Reserve system

I spent much too long removing reserved users from solr and then reverting those changes.

In any case, users who are in reserve are not sent saved search emails. I also added a check of in_reserve to User.can_receive_myjobs_email to hopefully prevent additional emails.

I may have missed a few bits and am open to suggestions.

All tests pass.
That was before my time. I'm not sure why it's like that.

In any case, the parts of this PR that consist solely of PEP8 were to help @almathew diagnose Jenkins.