Modifications for Mocking Instagram

This modiications allows to mock instagram with custom and programmable http server such as https://github.com/robfrank/http-mock.

Without this modifications, when making tests, the Library always goes to the Instagram public API. This way I cannot mock the Instagram API and cannot make predictable tests. This modifications allows me to run an embeded http server that delivers preditable responses, allowing me to make tests of classes that use the jInstagram library.