reverting decoupling of NumberHelper from safe_join and adding tests for escaping of delimiters and separators

The docs suggest that the middleware stack is an Array, so I've added
the unshift method to it. Originally I added some more Array methods,
but it was agreed that they lacked usecases.

Fix incorrect assert_block -> assert conversion. Assumed too much from the MiniTest deprecation message.

Fixes #2394

Change prompt to options hash in grouped_options_for_select

Revert "Revert "Remove `:disable_with` in favor of `'data-disable-with'` option from `submit_tag`, `button_tag` and `button_to` helpers.""

Finally remove `:disable_with` but use `:data => { :disable_with => ... }`
in examples to show off a better API (which looks nicer in Ruby 1.9)

This reverts commit a5c38a9c.

Revert "Remove `:disable_with` in favor of `'data-disable-with'` option from `submit_tag`, `button_tag` and `button_to` helpers."

`disable_with:` is much easier to type than `"data-disable-with" =>`,
and the fact it uses "data-disable-with" => is an implementation concern,
it should not affect the public API.

This reverts commit 683fc4db.

Remove `:disable_with` in favor of `'data-disable-with'` option from `submit_tag`, `button_tag` and `button_to` helpers.

using split_paragraphs method and content_tag instead of string
concatination

Support data: url scheme

Conflicts:
	actionpack/lib/action_view/asset_paths.rb

Introduced in 0f848dd5.

* Remove template assignment: there is no need for this assignment,
  given we are rendering a collection with possibly different templates,
  and a second call to render (with the same instance) would behave
  differently if the template is set.
* Remove segments array in favor of Array#map
* Use local vars whenever possible
* Cache local template keys, remove defaults from find_template

the select method (tag select) forces :include_blank  if is required and no multiple and
display size is one

and display size 1 and not multiple attribute,  Fixes #5908

Changed /images and /fonts to /assets in the examples of
image_path, image_tag and font_path helpers

[ci skip]

This reverts commit 667d0bdd, reversing
changes made to 4ae6bab6.