Use SPM correctly

Fix travis

Create AutoReleasingCarrier class to reduce boilerplate

Fix pointer type

Implement convertible types which greatly reduces verbosity

Add support for datetime values

Some source from SwiftFoundation was copied :)

Remove dependency on SwiftFoundation

I'm just trying to make things work. This is by no means
a good solution.

updated Travis CI

removed BSON.Error.Domain

fixed BSON.Binary