Added generic http actions for get/post/put/patch to make adding custom actions on a resource easier
Added $url and $delete methods
Updated docs for new $get, $post, $put, $patch, $delete, $url methods.
Added default Content-Type setting to make sure that patch sends application/json.
Merge pull request #20 from tpodom/generic_http_actions

Fixes #19 - Adds generic http actions to help with customizations