[2.6] Remove possible call_user_func()
[2.3] Remove possible call_user_func()
[2.5] Remove possible call_user_func()
[Process] Remove deprecated methods
[Console] improve deprecation warning triggers

Since the default helper set of the Console `Application` relies on
the `DialogHelper`, the `ProgressHelper` and the `TableHelper`, there
must be a way to not always trigger `E_USER_DEPRECATION` errors when
one of these helper is used.
fixed a test
updated CHANGELOG for 2.3.23
update CONTRIBUTORS for 2.3.23
updated VERSION for 2.3.23
bumped Symfony version to 2.3.24
updated CHANGELOG for 2.5.8
update CONTRIBUTORS for 2.5.8
updated VERSION for 2.5.8
bumped Symfony version to 2.5.9
updated CHANGELOG for 2.6.1
updated VERSION for 2.6.1
bumped Symfony version to 2.6.2
CS fixes
Removed unused imports
minor #12837 [2.3] CS Fixes And Removed Unused Imports (GrahamCampbell)

This PR was merged into the 2.3 branch.

Discussion
----------

[2.3] CS Fixes And Removed Unused Imports

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

##### This pull request fixes some cs issues in symfony 2.3.

As far as I understand, symfony's coding standards dictate that there should be no blank lines between imports and imports should not be prefixed with a slash. There are one or two other tiny fixes in here too.

Also, we should only import things that we actually *use*. :)

Commits
-------

0e4f0e7 Removed unused imports
0fc3369 CS fixes