[Finder] added Finder::ignoreUnreadableDirs() method
[CS Fix] Consistent coding-style of concatenation operator usage
Enforce sprintf for exceptions
added missing license blocks
Merge branch '2.2'

* 2.2:
  added missing license blocks
  added missing license blocks
merged branch jfsimon/issue-6981 (PR #7518)

This PR was merged into the master branch.

Discussion
----------

[Finder] adds a way to ignore AccessDeniedException

This PR adds a `Finder::ignoreUnreadableDirs()` method which tells `Finder` to ignore unreadable directories instead of throwing an `AccessDeniedException`.

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #6981

Commits
-------

a63b30b [Finder] added Finder::ignoreUnreadableDirs() method
[Finder] updated CHANGELOG
Merge remote-tracking branch 'symfony/master' into develop

Conflicts:
	Adapter/PhpAdapter.php
	CHANGELOG.md
	Exception/ExceptionInterface.php
	src/main/php/ehough/finder/adapter/AbstractFindAdapter.php
	src/main/php/ehough/finder/adapter/BsdFindAdapter.php
	src/main/php/ehough/finder/adapter/GnuFindAdapter.php
	src/main/php/ehough/finder/iterator/RecursiveDirectoryIterator.php
	src/main/php/ehough/finder/shell/Command.php