Fixes skipping object callback filters

This allows you to skip callbacks that are defined by objects, e.g. for
`ActionController`:

    skip_after_filter MySpecialFilter

Previously this didn't work due to a bug in how Rails compared callbacks
in `Callback#matches?`. When a callback is compiled, if it's an object
filter (i.e. not a method, proc, etc.), `Callback` now defines a method on
`@klass` that is derived from the class name rather than `@callback_id`.
So, when `skip_callback` tries to find the appropriate callback to
remove, `Callback` can regenerate the method name for the filter
object and return the correct value for `Callback#matches?`.
Removing tests for deprecated options in active support. The
+use_full_path+ option was removed in 3b3790a4 and passing the template
handler to render was deprecated in 43d27e91.
Merge pull request #10283 from wangjohn/remove_tests_for_deprecated_options

Removing tests for deprecated options in active support.
Added tests for if condition in Active Model callbacks
Merge pull request #10284 from neerajdotname/missing-active-model-tests

Added tests for if condition in Active Model callbacks
fix wrong test description and failure message
Merge pull request #10286 from neerajdotname/fix-wrong-test-name-and-failure-message

fix wrong test description and failure message
fix README links in the main README.md
Merge pull request #10289 from maratvmk/readme

fix README links in the main README.md
extract path into variable
Merge pull request #10290 from buddhamagnet/master

Extract path into variable
extract array to a constant
Merge pull request #10293 from vipulnsward/dont_mutate_callback

extract array to a constant
Merge pull request #10096 from benofsky/fix_skipping_object_callback_filters

Fixes skipping object callback filters
Move CHANGELOG entry to top

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