Install Spring preloader when generating new applications
minor 4_1_release_notes changes. [ci skip]
Merge pull request #12958 from jonleighton/spring

Install Spring preloader when generating new applications
add Spring as major feature in the 4.1 release notes. [ci skip]

Follow up to #12958.
remove variants paragraph indent in release notes. [ci skip]
Fix documentation of number_to_currency helper

Now users have to explicit mark the unit as safe if they trust it.

Closes #13161

Conflicts:
	actionpack/lib/action_view/helpers/number_helper.rb
	actionpack/test/template/number_helper_i18n_test.rb
Add failing test for using simple_format without OutputSafetyHelper available
Fix issue where TextHelper#simple_format would try and call missing 'raw' method