Fix email validation error I18n symbol lookup

And include %{value} for interpolation in validation messages.

The current code hardcodes the I18n key and improperly assigns the error
which leads to several problems:
* You cannot override the translation message for models/attributes
* You cannot pass your own I18n key as a symbol (eg. :invalid_email)
* You cannot use symbol interpolation

This fixes the above problems and is the proper solution for issue #2346.

This fix also applies to 1-2-stable and 1-3-stable.
For a fix against 1-1-stable see PR #2729.

Fixes #2730
nested_taxons_path will now take a Taxon object and generate a proper URL
Fixes orders#show title for i18n cases

Fixes #2784
When a calculator is using a preference of type :text, a textarea is shown. The calculator.js should disable/enable this textarea the same as the input from a preference of any other type.

Fixes #2782
Correct content length check in base_helper_spec test for meta_data_tags
Switch the mailers to be invoked using ids, not model objects. This makes it easier to support asynchronous mail jobs, as only simple ids need to be persisted.

Fixes #2806
Revert premature merging of #2806

Revert "Switch the mailers to be invoked using ids, not model objects. This makes it easier to support asynchronous mail jobs, as only simple ids need to be persisted."

This reverts commit a3f1d3bbaf841a735a8697133ed12870bb446148.