[Doc] Use Markdown syntax highlighting
Merge branch '2.3' into 2.5

* 2.3:
  [Doc] Use Markdown syntax highlighting
  [Finder] tweaked docs
  [Finder] Add info about possibilities offered by SplFileInfo
  fix components tests
  [Intl] FIxed failing test
  [Intl] Generated the data for ICU version 54-rc
  [EventDispatcher] fix doc bloc on EventDispatcherInterface
  [Validator] Update validators.zh_CN.xlf, fix translation error
  bumped Symfony version to 2.3.21
  updated VERSION for 2.3.20
  update CONTRIBUTORS for 2.3.20
  updated CHANGELOG for 2.3.20
  [Intl] Integrated ICU data into Intl component

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php
	src/Symfony/Component/Intl/ResourceBundle/LocaleBundle.php
Merge branch '2.5'

* 2.5:
  [Doc] Use Markdown syntax highlighting
  [Finder] tweaked docs
  [Finder] Add info about possibilities offered by SplFileInfo
  fixed CS
  [Security][Http][Authentication] Make a test pass on HHVM
  fix components tests
  [Intl] FIxed failing test
  [Intl] Generated the data for ICU version 54-rc
  [EventDispatcher] fix doc bloc on EventDispatcherInterface
  [Validator] Update validators.zh_CN.xlf, fix translation error
  bumped Symfony version to 2.5.6
  updated VERSION for 2.5.5
  updated CHANGELOG for 2.5.5
  bumped Symfony version to 2.3.21
  updated VERSION for 2.3.20
  update CONTRIBUTORS for 2.3.20
  updated CHANGELOG for 2.3.20
  [Intl] Integrated ICU data into Intl component

Conflicts:
	src/Symfony/Component/Debug/README.md
	src/Symfony/Component/DependencyInjection/README.md
	src/Symfony/Component/HttpKernel/Kernel.php
	src/Symfony/Component/OptionsResolver/README.md