gitignoring
Force "num" type, implement api.post

* Add api.post handling
* Force the "num" type in both Post and Index requests
Add some (not very) useful text in exceptions creation
Now "index" executable does something useful.
Add post_details

Usage: ./post_details http://archive.moe/board/thread/threadnum/#postnum
Add new executable: thread_details

Usage: ./thread_details http://archive.moe/a/thread/112792840/#112792840
Add PostNotFound exception, GenericError now tells you the error

* Add PostNotFound exception
* In the text of GenericError, you can find the server response
new Board object, bugfix on media=null, thread!=index

* Add Board object
* bugfix: In a post, if "media" is "null", it does no longer crash.
* bugfix: Response from /thread and /index is different.
As we reuse the Thread object, we need to handle the
different behaviour.
Now using the full power of requests (aka: I'm dumb)

Now using the "parameters" parameter when issuing an HTTP request.
Minor modifications