Updated aggregation tests to use non-deprecated API and make tests pass (#747)
Updated aggregation tests to use non-deprecated API and make tests pass (#747)

Updated code to use non-deprecated API and fix tests

- changed all uses of the deprecated `.aggregate(...)` API to `.aggregateWith1(...)`
- added explicit types so that IntelliJ IDEA is happy
cchantep/ReactiveMongo,ReactiveMongo/ReactiveMongo,ReactiveMongo/ReactiveMongo,ornicar/ReactiveMongo,cchantep/ReactiveMongo,ornicar/ReactiveMongo