Fixup/cleanup

Great gem! It was blowing up for me on `BggApi.new` because my IRB was setup to use the awesome_print gem. I found out I could reproduce the issue just by calling a non-existent method:
```
bgg = BggApi.new
bgg.foo
TypeError: exception class/object expected
	from /Users/strathmeyer/.rvm/gems/ruby-2.0.0-p195/bundler/gems/bgg-api-8be15cb6273f/lib/bgg-api.rb:66:in `raise'
	from /Users/strathmeyer/.rvm/gems/ruby-2.0.0-p195/bundler/gems/bgg-api-8be15cb6273f/lib/bgg-api.rb:66:in `call'
```

Basically, it gets a non-200 response, and tries to raise the response code (an integer). You can get the same thing in IRB by running `raise 1`. Commit 929b12d fixes this issue by defining specific methods, instead of using `method_missing`.

Commit 911e8ce fixes a different bug where not all the alternate names are returned.

Along the way, I modernized one of the spec files, fixed up the README, and figured out how to get around calling `HTTParty.` explicitly. 

Merge the whole PR or take the pieces you want!

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