Add active_support/testing/autorun

minitest/autorun load minitest/spec polluting the global namespace with
the DSL that we don't want on Rails
Remove unneeded tests

These tests are needed only if we are using MiniTest::Spec
Do not use the same tests description
Alias refute methods to assert_not and perfer assert_not on tests
Add note on the contributing guide to not use the refute methods
Merge branch 'minitest_cleanup'
Merge pull request #8666 from mekishizufu/fix_lambdas

Fix usage of lambda as a Rack endpoint
Do not install debugger in the pathlevel 362
Use ActiveSupport::TestCase in the journey tests
refatctoring of some code repetition in spawn_methods
Revert "Do not install debugger in the pathlevel 362"

This reverts commit 9c18b6a818801a77a90c2768e436e4690537a3ab.
Merge pull request #8664 from acapilleri/spawn_method

refatctoring of some code repetition in spawn_methods
Add source extract to detailed exception page
Only call MiniTest.autorun if the dependecy is present
Styling for exception page
Add new style to Routing Error page
Improve line-height to have better line spacing in exception message
Updated copyright notices for 2013
Add style to AV::Template::Error exception page
Fix test for DebugExceptions due to template change