Allow to pass the `adapter` option in initializer, pass it to HTTPI when fetching remote WSDL

[Envek]

It will be useful for those people who need to use different HTTPI adapters for different services, see savonrb/savon#564

I've bumped gem version as there is related pull request in savon that depend on it: savonrb/savon#566.

I don't know, how to test this, please tell me any ideas and suggestions, I'll write tests and append it to this request.

[tjarratt]

Just thinking out loud, but it seems like the best way to test this might be to make a fake adapter that just records calls, then you could have an assertion that the fake adapter was called at some point with the expected arguments.

The fake might look something like this... (shamelessly stolen from the httpi docs)

class FakeAdapter < HTTPI::Adapter::Base

  register :my_adapter, deps: %w(some_http_client)

  def initialize(request)
    @@requests ||= []
    @@requests.push request
    @request = request
    @client = SomeHTTPClient.new
  end

  attr_reader :client

  def request(method)
    @@methods ||= []
    @@methods.push method
    response = @client.request(method, @request.url, @request.body)

    Response.new(response.code, response.header, response.content)
  end
end

# in test, you could assert on class variables after the requests have been made
expect(FakeAdapter.class_variable_get(:@@requests).size).to eq(1)
expect(FakeAdapter.class_variable_get(:@@requests)[0].url).to eq("http://example.org")
expect(FakeAdapter.class_variable_get(:@@methods)).to eq([:GET, :POST])

Also -- when this gets merged in, i'm probably going to bump the minor version number since this is a new feature. No need to bump it yourself.