Signed-off-by: NJosé Valim <jose.valim@gmail.com>

AS Xml and Json parsers expect the request body to be a real IO object
supporting methods like getc or ungetc which are not specified by the
Rack spec and aren't supported by Passenger or the Rewindable input
wrapper.

We can restore functionality if the AS parsers are rewritten to support
Racks subset of supported IO methods.

Remove find_with_associations and related code from associations now that Relation handles that stuff

Fix bug that causes TimeZone.seconds_to_utc_offset to returns wrong offset when hour < 0 and not in hundreds [#3741 status:resolved]
Signed-off-by: NJosé Valim <jose.valim@gmail.com>