Support for multiple filters for the certificate query.

[mik373]

I'd like to be able to ask for all certificates that are

1. active
2. issued by my authority
3. have certain domain
   and I expect the resulting SQL query to do an and for those conditions:

Starting here:
https://github.com/Netflix/lemur/blob/master/lemur/certificates/service.py#L246

I'd like the loop for terms - not an if statement and the query builder to add the conditions into the resulting query.