w2d2: Request new chunk

Read: http://worldmodscode.wordpress.com/2011/12/26/practical-garbage-collection-part-1-introduction/

Started on the main part of the buddy allocator.

reuest_chunk(info_item_t *root, int targetk);

Tests to cover this requesting zero levels down (targetk = k), one level down (targetk = k-1), two levels down (targetk = k-2) and all the way down (targetk = 0). Failing so far.