pass in MongoDatabase instead of Collection
moved Method related tests into namespace
added ability to set collection name

made MongoCollection internal on MongoDbApiOutputCache
set friend assembly in AssemblyInfo
made the Key property the _Id of the document
Save (instead of insert) to provider Upsert functionality
When inserting item with same key, it's updated
does not return item if expired
on get, delete item from cache if it's expired.
Can also use TTL collections for this
created BsonClassMap - removed annotations from poco
cahce to cacheCollectionName param
more descriptive
changed Expiration to ExpireAt - made DateTime
removed parameterless ctor on CachedItem - everything should have an ExpireAt
added TTL index on collection
test takes over 1 minute to run, because of the way TTL collections are cleared!