Retrieve a user's WoW character list

[nmccrory]

A call to client.Profile().WoW() fetches a list of a user's WoW characters. The addition of the WoW characters endpoint wraps up the Battle.net Profile API.

Going forward, I'm thinking it would be best to put SC2, WoW, and potentially D3 libraries into their own packages within the repo as they are going to be fairly large... how do you feel about making this change? @mitchellh

[mitchellh]

@nmccrory I agree. A good red flag is that you have a lot of WoW and SC2-prefixed structs. :) that's usually a good indicator it is time for a package. Do you want to just do that and reopen a new PR? Or do you want me to merge this first? It looks great.

[nmccrory]

@mitchellh I can go ahead and put them both into their own packages. Earlier I attempted this and ran into issues trying to consume client_test.go (methods like setup() and teardown()) from within a package. Would best practice be to create a new client.go and client_test.go for each package we add?