Make sure that _search/scroll request path does not include index

It turns out that while you call the _search endpoint you embed
index and type name in the URI path, but when requesting the
_search/scroll endpoint it should be directly below the elasticsearch
base uri. This change also introduces error reporting if a http
request fails.
Merge pull request #10 from noaresare/pr/scroll-req-fix

Make sure that _search/scroll request path does not include index