Support for additional data types, loading from specified json path.

Added support for:
* Integers
* Floats
* Booleans
* Arrays (Strong and weak typed)
* Maps
* Populating interface from config key

Config paths are no longer hardcoded to "gofig.json", Calling gofig.Load(path) returns a Config object with values loaded from that path.

Edit: Also added godoc comments for documentation.