Projection handling of $vector

[maheshrajamani]

Support $vector field in projection

Eg:
{ "find": { "filter" : {"name": "Coded Cleats"}, "sort" : {"$vector" : [0.15, 0.1, 0.1, 0.35, 0.55]}, "projection" : {"$vector" : 1}, "options" : { "limit" : 1 } } }