[HttpFoundation] use different approach for duplicate keys in postgres, fix merge for sqlsrv and oracle
updated CHANGELOG for 2.3.16
update CONTRIBUTORS for 2.3.16
updated VERSION for 2.3.16
updated CHANGELOG for 2.4.6
updated VERSION for 2.4.6
updated CHANGELOG for 2.5.0
updated VERSION for 2.5.0
Fix a parameter name in a test
bumped Symfony version to 2.3.17
bumped Symfony version to 2.4.7
bumped Symfony version to 2.5.1
[Debug] fix wrong case mismatch exception
minor #11026 [Validator] Fix a parameter name in a test (elnur)

This PR was merged into the 2.3 branch.

Discussion
----------

[Validator] Fix a parameter name in a test

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | not required

Commits
-------

069e925 Fix a parameter name in a test
Remove undefined variable $e
bug #11041 Remove undefined variable $e (skydiablo)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #11041).

Discussion
----------

Remove undefined variable $e

This PR was submitted on the symfony/DependencyInjection read-only repository and moved automatically to the main Symfony repository (closes symfony/DependencyInjection#6).

Commits
-------

637c6e1 Remove undefined variable $e
[Serializer] fixed bc-break with cdata-section nodes
bug #11044 [Serializer] Fix BC break since 2.5 (fieg)

This PR was merged into the 2.5 branch.

Discussion
----------

[Serializer] Fix BC break since 2.5

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

We spotted a BC break after upgrading to 2.5. The break seems to originate from PR #10668 and I hereby submit a test that passes if I revert the XmlEncoder.php back to before the PR.

The result of the given decode call currently is (notice the "#cdata-section"):

```php
array(1) {
  'firstname' =>
  array(1) {
    '#cdata-section' =>
    string(12) "Paul <or Me>"
  }
}
```

I am looking for help fixing the issue, because so far I wasn't able to come up with a fix. @csarrazi as an author of the PR, do you perhaps have any thoughts on this matter?

Commits
-------

48d9f36 [Serializer] fixed bc-break with cdata-section nodes
bug #11033 [Debug] fix wrong case mismatch exception (nicolas-grekas)

This PR was merged into the 2.5 branch.

Discussion
----------

[Debug] fix wrong case mismatch exception

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #11030
| License       | MIT
| Doc PR        | none

Commits
-------

8e9cc35 [Debug] fix wrong case mismatch exception
[Debug] fix debug handlers config