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