Changed date format of footer in the Plans pdf export to a more human readable date, ...

e.g., "Last modified 26 April 2019".

Changes:
  - added :readable date format to language locales
  - used this date for the footer in the Plans pdf export.
    Note, changed " formats" to "format" and use :readable in footer date
     From  "date: l(@plan.updated_at.to_date, formats: :short)" -->
     to    "date: l(@plan.updated_at.to_date, format: :readable)"
  - to pass Rspec test spec/features/plans/exports_spec.rb we needed to add
    a locale file en.yml  which is a copy of en-GB.yml to avoid error
    "1) PlansExports User downloads their plan as PDF
     Failure/Error: date: l(@plan.updated_at.to_date, format: :readable)

     I18n::MissingTranslationData:
       translation missing: en.date.formats.readable"

Fix for Issue #2094.

Update CSV downloads with consistent date format ...

Fixes #1936

Added I18n formats date.formats.csv to allow for regional customisation

Sync all translations & locales

Merge branch 'final_schema' of https://github.com/DigitalCurationCentre/roadmap into final_schema

.pot and .po files re-generated

Updated projects_helper by renaming 'project_list_column_body' to 'plan_list_column_body'. updated references to that code block. moved hard-coded 'Unknown' to locale files. Added tests for projects_helper

unit tests for notes and answers. addded new validator to check whether the question's template matches the plans template

resolved merge conflicts

extracted plan visibility work out of dev branch for PR to DCC

switched visibility over to an enum. updated the project objects accordingly. Added some more unit tests. Updated locale files with visibility text

fixed functional tests on static_pages controller

finsihed adding visibility to project details page as radio button options. Updated public DMPs page to work with new visibility and moved it to the static pages controller since it falls outside of normal security. Updated all locale files accordingly

Added locale specific column headers for new visibility column. Made the new column NOT a default

Added logic to display the correct visibility based on whether the project is_test or is_public or neither

updated locale files so that helpers.yes and helpers.no work. Those are yaml keywords so they must be quoted (e.g. 'yes': 'Oui' instead of yes: 'Oui'). Added is_public and is_test checkboxes to projects edit/create forms

Added magic strings and identifier schemes to new ES locale file. Updated names of magic string categories so that they match the table names

add spanish translations