Leveraging generics and type inference for common db functions
CHECKPOINT: More progress on leveraging generics and type inference a few failing tests left
Added new API methods and fix

Added TryGet and ContainsKey methods and extensions.
Fixed condition in ConverterExtensions.EnsureCorrectSize

Closes #14
Closes #15
Merge pull request #16 from ilyalukyanov/converters

Converters alternative to providers base classes and static state