Match hardened site HTTP headers case insensitive (#1425)
Match hardened site HTTP headers case insensitive (#1425)

File app/lib/hardened_sites_detective.rb checks for hardened sites.
However, HTTP field names are case-insensitive, see RFC 2616 section 4.2,
and we weren't compensating for that properly

This commit downcases all HTTP header fields before considering them,
so that HTTP headers can be correctly considered while ignoring case.

This should fix #1253.

Signed-off-by: David A. Wheeler <9ae72d22d8b894b865a7a496af4fab6320e6abb2@dwheeler.com>
coreinfrastructure/best-practices-badge,coreinfrastructure/best-practices-badge,linuxfoundation/cii-best-practices-badge,coreinfrastructure/best-practices-badge,linuxfoundation/cii-best-practices-badge,coreinfrastructure/best-practices-badge,linuxfoundation/cii-best-practices-badge,linuxfoundation/cii-best-practices-badge