This helps to not break on plugins having require "gravatar"
in their init.rb. This statement is not needed anymore in any
supported version of ChiliProject (or Redmine for that matter) and
should thus be removed from all plugins.

having a fixed call order resolves a problem where
'value=' was called before 'name=' resulting in no
serialization

Contributed by Steffen Schüssler

Contributed by Harald Klimach

Contributed by Harald Klimach

Up until now, the patch used to be a no-op. While the filters class
attribute was set correctly, the methods using it were not actually
overridden as they are only included above the existing methods in
the module chain.

This resulted in an arbitrary load order of filters on Ruby 1.8. As
such, our overridden standard filters might not have actually
overridden anything.

Still, the patch can be completely removed once we either require
Ruby 1.9 (as we have ordered ahshes by default then) or once
https://github.com/Shopify/liquid/pull/87 was merged and released
upstream.

Adapted from
https://github.com/redmine/redmine/commit/28f9605fe2e242cc917108c277d8d6d6db3cdae1
by Jean-Philippe Lang