SERVER-11138 Try to stabilize replsets/temp_namespace.js

Test is for SERVER-10927
Don't require a pointer to BSONElement in pipeline parsing.

Prevents use of rvalues among other annoying issues.
SERVER-10613 Optimize initial $redact/$match pair

If possible, inserts a subset of the $match before the $redact to enable
index usage and reduce the number of documents that need to be examined.