Fix Action Mailer changelog indenation to match other changelogs

Also some minor improvements to other changelogs. [ci skip]

actionmailer/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
-* Explicit multipart messages no longer set the order of the MIME parts.
-  *Nate Berkopec*
+*   Explicit multipart messages no longer set the order of the MIME parts.
+    *Nate Berkopec*
 
-* Do not render views when mail() isn't called.
-  Fix #7761
+*   Do not render views when mail() isn't called.
+    Fix #7761
 
-  *Yves Senn*
+    *Yves Senn*
 
-* Allow delivery method options to be set per mail instance *Aditya Sanghi*
+*   Allow delivery method options to be set per mail instance *Aditya Sanghi*
 
-  If your smtp delivery settings are dynamic,
-  you can now override settings per mail instance for e.g.
+    If your smtp delivery settings are dynamic,
+    you can now override settings per mail instance for e.g.
 
-      def my_mailer(user,company)
-        mail to: user.email, subject: "Welcome!",
-             delivery_method_options: { user_name: company.smtp_user,
-                                        password: company.smtp_password }
-      end
+        def my_mailer(user,company)
+          mail to: user.email, subject: "Welcome!",
+               delivery_method_options: { user_name: company.smtp_user,
+                                          password: company.smtp_password }
+        end
 
-  This will ensure that your default SMTP settings will be overridden
-  by the company specific ones. You only have to override the settings
-  that are dynamic and leave the static setting in your environment
-  configuration file (e.g. config/environments/production.rb)
+    This will ensure that your default SMTP settings will be overridden
+    by the company specific ones. You only have to override the settings
+    that are dynamic and leave the static setting in your environment
+    configuration file (e.g. config/environments/production.rb)
 
-* Allow to set default Action Mailer options via `config.action_mailer.default_options=` *Robert Pankowecki*
+*   Allow to set default Action Mailer options via `config.action_mailer.default_options=` *Robert Pankowecki*
 
-* Raise an `ActionView::MissingTemplate` exception when no implicit template could be found. *Damien Mathieu*
+*   Raise an `ActionView::MissingTemplate` exception when no implicit template could be found. *Damien Mathieu*
 
-* Asynchronously send messages via the Rails Queue *Brian Cardarella*
+*   Asynchronously send messages via the Rails Queue *Brian Cardarella*
 
-* Allow callbacks to be defined in mailers similar to `ActionController::Base`. You can configure default
-  settings, headers, attachments, delivery settings or change delivery using
-  `before_filter`, `after_filter` etc. *Justin S. Leitgeb*
+*   Allow callbacks to be defined in mailers similar to `ActionController::Base`. You can configure default
+    settings, headers, attachments, delivery settings or change delivery using
+    `before_filter`, `after_filter` etc. *Justin S. Leitgeb*
 
 Please check [3-2-stable](https://github.com/rails/rails/blob/3-2-stable/actionmailer/CHANGELOG.md) for previous changes.

activemodel/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
+
 *   Add `ActiveModel::Validations::AbsenceValidator`, a validator to check the
     absence of attributes.
 

activerecord/CHANGELOG.md

@@ -5,7 +5,7 @@
 
     *Yves Senn*
 
-*   Add ability for postgresql adapter to disable user triggers in disable_referential_integrity.
+*   Add ability for postgresql adapter to disable user triggers in `disable_referential_integrity`.
     Fix #5523
 
     *Gary S. Weaver*

activesupport/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
-*   Remove surrogate unicode character encoding from ActiveSupport::JSON.encode
+
+*   Remove surrogate unicode character encoding from `ActiveSupport::JSON.encode`
     The encoding scheme was broken for unicode characters outside the basic multilingual plane;
-    since json is assumed to be UTF-8, and we already force the encoding to UTF-8 simply pass through
-    the un-encoded characters.
+    since json is assumed to be `UTF-8`, and we already force the encoding to `UTF-8`,
+    simply pass through the un-encoded characters.
 
     *Brett Carter*