Improve SSL checking

Extending @rtsio's fix in 7e95fe8ce2ffdf6a8ce5ff5f1be4b78b7c79ee93 to
all other HTTPS checks.
Make more explicit the nesting of HTTPS conditionals
Only prepopulate edition name/slug as placeholder text

Minor modification to 3e4e227.
Always set INCLUDE_PATH

Turning 3126c3f on its head, set `INCLUDE_PATH` every time, rather than
sometimes only setting `$include_path`.