[INPROGRESS] First version of tokumx converter

This pull request aims to add tokumx support to mongoriver by converting tokumx oplog records to mongo oplog records.

cc @ebroder 
Ok, so I should store the BSON::Binary and do comparisons based on that? Do you have any state on how that works, what is stored in the binary and is it guranteed that it will be monotonically increasing?

Also, what would be a good strategy for extracting latest? Timestamp or assume again that the _id's are increasing?