feature #19997 inlined some CSS (fabpot)

This PR was merged into the 3.2-dev branch.

Discussion
----------

inlined some CSS

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

This PR has several goals:

* It fixes the discrepancy between where CSS files were stored (FrameworkBundle) and where there were used (TwigBundle);

* It removes the need to install the assets to get exceptions (think Silex, micro-kernel-based-edition, ...);

* It makes things consistent with how we already manage images for exceptions (they are inlined);

* It makes things consistent with how we manage assets for the web profiler.

Commits
-------

f354638 inlined some CSS

src/Symfony/Bundle/FrameworkBundle/CHANGELOG.md

@@ -4,6 +4,7 @@ CHANGELOG
 3.2.0
 -----
 
+ * The `Resources/public/css/*.css` files have been removed (they are now inlined in TwigBundle)
  * The `Controller::getUser()` method has been deprecated and will be removed in
    Symfony 4.0; typehint the security user object in the action instead.
  * Added possibility to prioritize form type extensions with `'priority'` attribute on tags `form.type_extension`