* add core spec
* improve authenticate method
* use switch instead of if branch
* set Github#auth to false in case of invalid authentication values
* post an info message in case Github#auth is set to false
Switch to firefox as test browser because PhantomJS doesn’t provide
response headers which are important for communicating with Github eg.
rate-limiting and link headers are very important.
And because it is the standard browser on Travis
* add pagination tests to core spec
* use simple string as url instead of new URL constructor
* check authorisation when requesting page
* new dist files