first pass working on async though just curl and select()

* Trying pull request
* New Branch for feature
* Version 1 of async fetching of data using curl_multi_perform, curl_multi_fdset and select.
** curl_multi_perform: starts the fetching process.... and returns how many easy url handles are left to be processed.
** curl_multi_fdset sets file descriptors for our application to track when our fd is ready with data.
** select(): unix system call to block untill the corresponding fd is ready. This fixes the previous issue of continuous running while loop.

Next Steps:
* clean code
* comment code
* implement url fetching in a separate thread than the main render thread.