Ability to fetch multiple objects with a single `PokeApi#get` call

[Ryan Workman]

PokeApi#get should be able to take multiple NamedApiResource queries and return a list of the results.

Ex:

PokeApi.get(pokemon: 'pikachu', item: 'potion', pokemon_species: 151)
# => [ <PokeApi::Pokemon .....>, <PokeApi::Item......>, <PokeApi::PokemonSpecies.....>]