Merge pull request #2499 from WouterJ/commit_comments_20

Fixed Commit comments
Merge pull request #2529 from fabpot/apache-authorization

added a note about php-cgi and Apache
[#2529] Minor tweak thanks to @WouterJ
Merge pull request #2549 from fabpot/browserkit-client

updated documentation for BrowserKit
Merge branch '2.0' into 2.1
Merge branch '2.1' into 2.2
Merge branch '2.2'
Merge remote-tracking branch 'origin/master'
[#2555] Tweaking JSON Hijacking note to add a bit more information that Fabpot added
Merge pull request #2481 from WouterJ/doc_standards

Refactored Doc standards
[#2481] Tweaks to new docs standards doc
removed non-MIT/BSD licensed code from Symfony SE
Adds documentation for the new ISSN validator
added doctrine tags to reference
added assetic DIC tags
remove the security.listener.factory DIC tag
Merge pull request #2434 from WouterJ/add_remove

Refactored docs to use adders/removers
Fixing outdated reference to the form "field" type
[#2434] Rearranging some new notes about adders and removers in the collection type
Merge pull request #2480 from pvolok/assetic_tags

Add assetic DIC tags reference.