Revert "CSHARP-663: Move caching of proxy objects to
MongoServerProxyFactory." This change has been rescheduled for version
2.0.

This reverts commit 207a824f30dca891d582f324273eb506d89d0fba.
CSHARP-603: changes from MONGO-CR to MONGODB-CR per server.
CSHARP-695: respect maxMessageSizeBytes when provided by the server.
CSHARP-594: Fixed the CSharp624Tests.TestKeyIsNotAString so it can run successfully regardless of the regional settings
CSHARP-661: Fixed documentation comments for FindOne and FindOneAs.
CSHARP-603: added security attributes to methods to mark them as SecurityCritical or SecuritySafeCritical, depending on context.
CSHARP-694: Provide a way to be more lenient about UTF8 validity.
CSHARP-694: Change values in unit tests to use values that fail in the same way in Mono as in .NET.
CSHARP-685: Initial implementation of GeoJson object model.
CSHARP-694: Added unit tests for using different Encodings with JsonReader(Writer). Realized that the Encoding is actually set at the StreamReader(Writer) level so JsonReader(Writer)Settings don't need an Encoding property.
CSHARP-685: Added doc comments to GeoJson object model.
CSHARP-684: added builder support for setOnInsert and the push each variants.
CSHARP-693: InsertBatch must call GLE after all sub-batches even if WriteConcern is Unacknowledged but ContinueOnError is false.
CSHARP-683: added support for elemMatch  in fields projection.
CSHARP-683: added query builder support for GeoJson queries.
cleaning up doc comments.
CSHARP-683: restricted within to be for only polygon types.
updated test and some doc comments.
CSHARP-687: changed signature of Combine methods to take an IMongoUpdate instead of an UpdateBuilder.
CSHARP-697: Keep SecureStrings secure and support non-ASCII characters in passwords.