Fixed bug in ChoiceType triggering a warning when not using utf-8

This fixes issue #10409 by not using json_encode anymore, but serialize
instead.
Added test case for 4c6a2d15095c13b2a35751b2b2712b183be489c4
bug #10568 [Form] Fixed hashing of choice lists containing non-UTF-8 characters (webmozart)

This PR was merged into the 2.3 branch.

Discussion
----------

[Form] Fixed hashing of choice lists containing non-UTF-8 characters

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10409
| License       | MIT
| Doc PR        | -

Commits
-------

18dc9a7 Added test case for 4c6a2d15095c13b2a35751b2b2712b183be489c4
73d56f7 Fixed bug in ChoiceType triggering a warning when not using utf-8
fixed CS
fixed the profiler when an uncalled listener throws an exception when instantiated
bug #10564 fixed the profiler when an uncalled listener throws an exception when instantiated (fabpot)

This PR was merged into the 2.3 branch.

Discussion
----------

fixed the profiler when an uncalled listener throws an exception when instantiated

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10371
| License       | MIT
| Doc PR        | n/a

When the profiler gets the uncalled listeners, the current page is broken without a very clear message. That happens when a listener is a service that depends for instance on the request; creating this service throws an exception.

After this patch, if we cannot get the listeners, we give up and add a log message about the problem (the error message is an info as the problem is not really related to the toolbar but more about how things work).

Commits
-------

79540d4 fixed the profiler when an uncalled listener throws an exception when instantiated
Fix class names in ApcUniversalClassLoader tests.
minor #10577 [ClassLoader] Fix class names in ApcUniversalClassLoader tests. (idn2104)

This PR was merged into the 2.3 branch.

Discussion
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[ClassLoader] Fix class names in ApcUniversalClassLoader tests.

[ClassLoader] These tests were failing due to a leading slash in the class name. Support for the leading slash in findFile was removed a while ago, but the Apc tests were not updated. See #10576 for more details.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10576
| License       | MIT
| Doc PR        | N/A

Commits
-------

dc0f8f9 Fix class names in ApcUniversalClassLoader tests.
[Process] fixed HHVM usage on the CLI
upgraded PHPUnit to version 4 for better HHVM support
fixed float comparison in unit tests for HHVM
bug #10579 HHVM fixes (fabpot)

This PR was merged into the 2.3 branch.

Discussion
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HHVM fixes

| 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

Fixes support for HHVM in the Process component and upgraded PHPUnit to version 4 for the same reason.

Commits
-------

9e6af95 fixed float comparison in unit tests for HHVM
73189b1 upgraded PHPUnit to version 4 for better HHVM support
8fbea0f [Process] fixed HHVM usage on the CLI
tweaked Travis configuration to get more tests running
minor #10578 tweaked Travis configuration to get more tests running (fabpot)

This PR was merged into the 2.3 branch.

Discussion
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tweaked Travis configuration to get more tests running

| 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 allows test for APC and tests for the French locales to be actually executed (they are currently skipped.)

Commits
-------

89742b0 tweaked Travis configuration to get more tests running
Fixes URL validator to accept single part urls
[Form] Added check for parent disabled status in Button form elements

The Button form element did not check for the parent disabled configuration status,
making them behave differently to all other form widgets.
[Form] Added test for disabling buttons
Use `Filesystem::chmod` instead of `chmod` when dumping file

This adds consistency as discussed in https://github.com/symfony/symfony/commit/ca5eea5c1922688685d104f962bc5d16626ce05d#commitcomment-5804089
bug #10591 [Form] Buttons are now disabled if their containing form is disabled (webmozart)

This PR was merged into the 2.3 branch.

Discussion
----------

[Form] Buttons are now disabled if their containing form is disabled

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #10109
| License       | MIT
| Doc PR        | -

Commits
-------

ebfee72 [Form] Added test for disabling buttons
6bb355e [Form] Added check for parent disabled status in Button form elements
minor #10590 [2.3] Use `Filesystem::chmod` instead of `chmod` when dumping file (romainneutron)

This PR was merged into the 2.3 branch.

Discussion
----------

[2.3] Use `Filesystem::chmod` instead of `chmod` when dumping file

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

This adds consistency as discussed in https://github.com/symfony/symfony/commit/ca5eea5c1922688685d104f962bc5d16626ce05d#commitcomment-5804089

Commits
-------

c2ffefd Use `Filesystem::chmod` instead of `chmod` when dumping file