provide a builder for form labels to customize wrapping around I18n content
add I18n support for `:placeholder` HTML option is passed to form fields
just use the placeholder tag value if it is passed as a String
Cache the value of `changed_attributes` when calling `changes_applied`

`changes_applied` calles `changes`, which will call `changed_attributes`
multiple times in a loop. This method actually performs work now, so we
should cache the results while looping over it when we know it cannot
change.
Fix guide anchor generation logic.

This could use in any translation because it's not limited to `[^a-z0-9]`.

Verify after this change, all guides still have same anchors.

[Robin Dupret & Juanito Fatas]
Merge pull request #16667 from JuanitoFatas/patch/anchor-generation

Fix guide anchor generation logic.
show stats for app/jobs
Raise ActiveJob::SerializationError when cannot serialize job arguments
Describe web-console in the release notes [ci skip]

I put a more up-to-date description of Web Console in the release notes.
I'm not really happy with the language, so if you guys can help me with
that I'll be grateful :)
Merge pull request #16671 from cristianbica/aj-raise-serialization-error

Raise ActiveJob::SerializationError when cannot serialize job arguments
Merge pull request #16674 from gsamokovarov/describe-web-console

Describe web-console in the release notes
[ci skip] Added documentation for has_many extension parameter
Grammer and spelling pass on web console release note. [CI SKIP]
Follow-up to #16560

For the sake of backward-compatibility, we need to make #instance_of?
return true for Fixnum. On the other hand, the method should still
give true for ActiveSupport::Duration itself which was not the case
before.
Skip #eql? tests on Rubinius for AS::Duration

Since Rubinius is relying on #instance_of? for its definition of #eql?
(http://git.io/MtmbbA) but ActiveSupport::Duration should behave like
is_a? it returns true with `Fixnum`.

Thus, for the moment, the last assertion is failing so we have to skip
this test.
Merge pull request #16676 from tgxworld/web_console_release_note_fixes

Grammer and spelling pass on web console release note. [CI SKIP]
Merge pull request #16675 from tomkadwill/has_many_documenting_extension_param

[ci skip] Added documentation for has_many extension parameter
Merge pull request #16673 from y-yagi/update_statistics_rake

show stats for app/jobs
Fix a few typos [ci skip]
Some tweaks to the development set-up guide

* Remove the libxml2 and libxslt part ; Nokogiri ships now with these
  libraries bundled.
* Add the missing installation instructions for either Arch Linux,
  FreeBSD or Mac OS X.
* Use the new `pkg install` syntax over `pkg_add -r` for FreeBSD 10+
  users.
* Point to the up-to-date version of PostgreSQL as for the BSD port.
* Make the platform installation instructions order consistent
  throughout the guide.
* Remove useless duplicated links to Homebrew's home.

[ci skip]