Refactored expected indices after email w/ mongo

Index key order has no bearing on key order in queries other than for multivalue ops such as `$gt`
Key order should be by greatest to least cardinality
Added sparse and unique declarations.

@feanil @cpennington 

At some point we should do some load tests on a prod clone w/ existing indices (copy index specs from prod if the cloning doesn't) and then test w/ these indices. @jzoldak 

I'd love to look at index stats but our version of mongo doesn't provide that info