[PDI-9620] MongoDB output does not configure write concern correctly resulting in an npe in some cases.
Merge pull request #7 from m-a-hall/master-bugFixes

[PDI-9620] MongoDB output does not configure write concern correctly resulting in an npe in some cases.
[PDI-9525] Support for MongoDB tag sets. Mongo (pun intended) checkin that adds support for read preferences with tag set(s) in MongoDbInput and custom write concerns (getLastError modes using tags) in MongoDbOutput. Both steps now have enhanced logging. Also snuck in a bonus new feature that allows all replica set members to be discovered automatically. Code has been refactored and cleaned up.
Merge pull request #8 from m-a-hall/master-tagSets

[PDI-9525] Support for MongoDB tag sets.