Renaming _edit templates to _fields

www.agileplannerapp.com/boards/173808/cards/5999

in subsequent changes, we'll keep only fields
in these templates, and move the form definition
to editions/show.html.erb. this commit only has
renames for easier review and reference.
Wrapping #edit tab-pane with edition form

www.agileplannerapp.com/boards/173808/cards/5999

The edition form contains edition activity
fields which are rendered in a modal when an
editor clicks a button to perform an activity
e.g. clicks "2nd pair of eyes".

Earlier when the form was rendered within the
first tab-pane, switching to another tab-pane
caused these edition activity fields to have
style 'display: none'. as a result, clicking
on an activity button didn't bring up a modal,
and just showed an overlay.

Now with the edition form wrapping the tab-pane,
the edition activity fields can be moved outside
the tab-pane. Moving across modals doesn't affect
the style of these activity fields, and so a modal
appears when performing an activity from any tab.

I've chosen to render all forms using the helper
`semantic_bootstrap_nested_form_for` because it is
just a wrapper over `semantic_form_for`, which adds
additional behavior like `link_to_remove` for nested
attributes.

Removed unused method `produce_fact_check_request_text`,
and unused class `no-auto-save` on smart answers form.
Bootstrap tab workarounds

www.agileplannerapp.com/boards/173808/cards/5999

Bootstrap tabs work as expected only if .tab-pane
elements are direct children of .tab-content. In
our case we're wrapping one .tab-pane in a form.

These fixes are required for bootstrap tabs to
continue working as expected.
Merge pull request #256 from alphagov/minor-issues-due-to-refactoring

Populate fact check notes and activity modal fix