Only accept actions without File::SEPARATOR in the name.

This will avoid directory traversal in implicit render.

Fixes: CVE-2014-0130
Preparing for 3.2.18 release
Fix broken tests of the previous release
Merge branch '3-2-sec' into 3-2-stable

Conflicts:
	actionpack/CHANGELOG.md
use fnmatch to test for case insensitive file systems

this is due to:

  https://bugs.ruby-lang.org/issues/5994
feature detect for FNM_EXTGLOB for older Ruby. Fixes #15053
Feature detect based on Ruby version.

I didn't want to do this, FNM_EXTGLOB is defined on 2.1.x, but Dir.glob
returns the wrong value on Ruby less than 2.2.0.  Checking for a
case-insensitive FS seems too hard, so just check Ruby version  Checking
for a case-insensitive FS seems too hard, so just check Ruby version.