League entry/request changes

* Made all the league request methods take multiple ids. This is an backwards-compatible change.
* Refactored get to use each_with_object. I think its slightly neater than initialising a variable, mutating it, then returning it. This isn't compatible with pre-1.9, but since 2.1.2 is the current stable version, I don't think this is a problem. I consider anything below 1.9.3 obsolete. If you don't agree, you can just pick the first commit.