[securelogin] Secure Login

Not sure what this is? It's already been ported.

Don't think I can call it release candidate yet as there are pending core bugs like #2595695: 4xx handling using subrequests: no longer able to vary by URL that if fixed would allow me to remove some workarounds, so setting to "beta" status.

Given the d8 release I'll have to release Secure Login as-is (the code I want to remove would cause a security vulnerability on 8.0.0).

Unfortunately, for sites on both HTTP and HTTPS there are in fact some issues in core regarding base URLs in render caches and aggregated CSS files causing mixed content warnings:

• #1377840: Caching does not properly respect protocol (a problem when dealing with https)
• #1494670: References to CSS, JS, and similar files should be root-relative URLs: avoids mixed content warnings & fewer bytes to send
• #2611420: Aggregated CSS assumes HTTP, causes mixed content warning when accessed via HTTPS

I ended up working around these issues by using hook_file_url_alter(): #2622382: Work around core bugs re: base URLs in render caches and aggregated CSS Fingers crossed things are basically working now, i.e. still needs more testing.