Add some basic tests of cache type supplied on init
user
```ruby
require_relative '../../test_helper'

class TestCache < Minitest::Test
  def setup
    @init_object = {
      server_url: 'http://b.com/parse',
      app_id: 'abc',
      api_key: 'def'
    }
  end

  def test_no_cache_ok
    assert Parse.setup(@init_object)
  end

  def test_moneta_transformer_accepted
    init = @init_object.merge(cache: Moneta.new(:LRUHash))
    assert init[:cache].is_a?(Moneta::Transformer)
    assert Parse.setup(init)
  end

  def test_moneta_expire_accepted
    init = @init_object.merge(cache: Moneta.new(:LRUHash, expires: 13))
    assert init[:cache].is_a?(Moneta::Expires)
    assert Parse.setup(init)
  end

  def test_bad_cache_type_rejected
    init = @init_object.merge(cache: 'hamster')
    assert_raises(ArgumentError) { Parse.setup(init) }
  end
end
```
assistant