code clean up

Game.cs:
-added documentation to some fields and methods
-changed getstat method to throw exception rather then to return an
"empty but not null" object
- added GetMatchResult method for a more simple way of getting the match
result
Champion.cs:
-named the datacontract to the correct name provided from the api
-changed all the Datamember fields to private from public and changed
the public interface to get only
-still needs documentation
Champions.cs
-Added a summary for the class
-changed DataContract to the name provided by the api
-changed DataMembers to private
-changed methods to indexers for searching champions by name or id