Removed wrong reference to cookbook

The /cookbook/request/mime_type article does not contain an example to
register a kernel listener since 2.5
Fixed bad indenting (the list was treated as a blockquote)
Fixed the format of one letter-based list
Fixed documentation for ProgressBar

This place is using the old ProgressHelper API and can be confusing when migrating.
Updating Symfony version from 2.4 to 2.5

The descriptions are still displaying the old version
Configuring composer.json to use the 2.5 version

Configuring composer.json to use the 2.5 version Rather than 2.4
quote YAML strings starting with % or @ characters

Pygment uses the YAML 1.1 standard to parse YAML code being highlighted.
A string value cannot start with the percent sign or the @ character
in YAML 1.1 without being quoted. To highlight the YAML code blocks
properly, strings starting with the percent sign are now enclosed in
double quotes.
remove "..." from XML element tags

The ellipses were used as placeholders in XML element tags. Thus, the
XML wasn't well-formed and therefore would have never been rendered
properly.
Update version in Rework your Patch section
link to the deployment index
apply headline guidelines to the cookbook articles
Added editorconfig
Fixed a minor syntax error
Also apply it for .rst.inc files
Remove "Controllers extends ContainerAware" best practice
feature #4009 Remove "Controllers extends ContainerAware" best practice (tgalopin)

This PR was submitted for the 2.5 branch but it was merged into the 2.3 branch instead (closes #4009).

Discussion
----------

Remove "Controllers extends ContainerAware" best practice

As discussed in https://github.com/symfony/symfony-docs/issues/4008, I remove the best practice consisting of extending ContainerAware instead of base Controller class to improve DX.

Commits
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992033f Remove "Controllers extends ContainerAware" best practice
Fix xml route configuration for routing condition

Current XML documentation doesn't respect routing schema (https://github.com/symfony/symfony/blob/master/src/Symfony/Component/Routing/Loader/schema/routing/routing-1.0.xsd)
bug #4012 Fix xml route configuration for routing condition (xavierbriand)

This PR was submitted for the master branch but it was merged into the 2.4 branch instead (closes #4012).

Discussion
----------

Fix xml route configuration for routing condition

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.4+
| Fixed tickets |  #4011

Commits
-------

6790fb2 Fix xml route configuration for routing condition
minor #4013 Removed wrong reference to cookbook (gquemener)

This PR was merged into the 2.5 branch.

Discussion
----------

Removed wrong reference to cookbook

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.5
| Fixed tickets |

The /cookbook/request/mime_type article does not contain an example to register a kernel listener since 2.5

Commits
-------

b8f27ef Removed wrong reference to cookbook
minor #4015 Fixed bad indenting (the list was treated as a blockquote) (javiereguiluz)

This PR was merged into the 2.3 branch.

Discussion
----------

Fixed bad indenting (the list was treated as a blockquote)

Commits
-------

d0c2880 Fixed bad indenting (the list was treated as a blockquote)