Upgrading Mongo From 3.x -> 3.2.1

Important note for sharded clusters!

3.2.1 has a bug in it for mongoc config metadata, if you upgrade there is a chance that you will run into this and need to downgrade your mongos client until there is a fix: BUG-SERVER-22247

Steps to upgrade:

• Upgrade each shard (mongod)
• upgrade the config servers starting with the last in the config string
• upgrade all mongos instances