ADFS improvements

use the configured attribute as the group name rather than
the DN

The equation was wrong.. exceeding means > not >=

Add ldap-search scope

* Support metadata XML directly in config
Also consider 'xml' as a key, in addition to 'url' and 'file'.
When provided, attempt to load this directly as a metadata XML string.
This is useful when working with dynamic configuration and external polling of metadata updates.

* Test loading XML from a fixed string
No preexisting test in this area
Adjust XML loader to only get global config in file mode - otherwise it is
unused, and it might pollute the test usage.
Test that an actully invalid config throws an exception, but that minimal valid
(albeit useless) XML is accepted.

Update copyright year from 2017 to 2018

Document IDPList option on saml20-idp-remote.php

Fix missing translation for metarefresh

Avoid db credentials in stack trace

PSR-2 lint fixes in lib/ directory

Add Mac support to salt generation command

Add PHP 7.2 into Travis

Fix missing single quote in example SP Config