[Cookbook] Fixed mapping of sessions cookbooks
[Cookbook][Session] Fixed headline in php_bridge
Updated images to match the new github design
Fixed typo
Removing note that used to be attached to a versionadded before it that was removed (and so this note should have been removed too)
Cookbook/Console/ConsoleCommand : Adding option/argument example in test

See comments in the PR #2792 I made on 2.1 branch
Adding a note to specify that parameter/option are not mandatory
Reference/forms/type/country : Minor bad copy/paste fix
Correct former TypeTestCase namespace
fix xml service definition

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | 2.3
| Fixed tickets | n.a.
remove useless use of variable
Change to @Wouterj proposal which is better
Fixing mishandling (sorry)
Rephrase the sentence about locale and language
Merge branch 'fix-cookbook_sessions_mapping' of git://github.com/iamdto/symfony-docs into iamdto-fix-cookbook_sessions_mapping

Conflicts:
	cookbook/map.rst.inc
Merge pull request #2771 from iamdto/fix-php_bridge_headlines

[Cookbook][Session] Fixed headline in php_bridge
Fixed AcceptHeader use example
Added node_paths /usr/lib/node_modules REQUIRED

I was testing, testing and testing one and another method or posibility, until I reached that page: https://github.com/kriswallsmith/assetic/issues/185 that opened my eyes, and one value was missing:

node_paths /usr/lib/node_modules

I continously received:
[exception] 500 | Internal Server Error | Assetic\Exception\FilterException
[message] An error occurred while running:
&#039;/usr/bin/node&#039; &#039;/tmp/assetic_styluswWvcnS&#039;
Error Output:
module.js:340
throw err;
^
Error: Cannot find module &#039;stylus&#039;

so, this fixes and finishes my 6 hours quest.
Updated for php array, pending review of xml
[#2775] Slight tweak because the node_paths actually has no default value