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.
Currently, that's the only way to tell for users created via the api without modifying the redirect project to send along more information. I have a feeling this may be going away anyway.