Fix. Make sure that scheme part of the URI is treated in a case-insensitive manner.

This is as per http://en.wikipedia.org/wiki/URI_scheme, and solves some
edges i.e., following (30x) URL from the "Location" header where we
have to deal with "HTTP://".

Signed-off-by: Krzysztof Wilczynski <krzysztof.wilczynski@linux.com>