fixes #18735 - truncate encryption key to match preferred length (#4350)

Ruby 2.4's OpenSSL bindings raise an ArgumentError during encryption if
the key length exceeds the cipher's configured length (32 bytes with the
default cipher), but the verification hash algorithm still uses the full...

fixes #18662 - stop default scope being overridden by association

Ensure the Taxonomix empty default scope isn't overridden by association
scopes which (effectively) calls `.where(:id => ...)` and overrides the
value of :id set in this default scope. This occurs on Rails 5.0 which...

fixes #18676 - don't ignore notification expiry

This also adds the ability to mass refresh expiry dates.

refs #17545 - notifications should be deleted with blueprint

fixes #18665 - call #to_h before comparing AC::Parameters to hash

Allows comparisons when ActionController::Parameters is separated from
Hash in Rails 5.0. #permit! is now called on inner hashes sent through
KeepParam (similar to rails/rails@e86524c in 5.1) so they are included...

Add pxe_loader to host REST

Add the field `pxe_loader` to the GET part of the hosts/
It is possible to set or update (POST, UPDATE), but not to read it

fixes #18664 - ignore missing callbacks in SmartProxyAuth concern

Filters that are only registered on the UI controllers cause errors
when using SmartProxyAuth on an API controller under Rails 5.0.

refs #17228 - modify, don't re-define existing constant

Prevents warnings during startup:

app/models/setting/provisioning.rb:9: warning: already initialized constant Setting::BLANK_ATTRS
    app/models/setting.rb:13: warning: previous definition of BLANK_ATTRS was here

Refs #17272 - fix sql condition

1==1 is not a valid SQL condition.

Fixes #18582 - add missing id params to taxonomy apidoc