Extract new base test class KernelTestClass

Ideal base class that needs access to a Kernel but not a Client such as
when testing a Command.
[FrameworkBundle] set a default value for gc_probability
Added a translation:debug command
[FrameworkBundle] Add HHVM support for built-in web server
feature #10017 [FrameworkBundle] Add HHVM support for built-in web server (RickySu)

This PR was squashed before being merged into the 2.5-dev branch (closes #10017).

Discussion
----------

[FrameworkBundle] Add HHVM support for built-in web server

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

Using HHVM as built-in web server for development from console.

```
hhvm app/console server:run
```

Commits
-------

66798ba9 [FrameworkBundle] Add HHVM support for built-in web server
[Translation] Added template for relative file paths
Added a ConcreteDumper
Changed placeholders
[FrameworkBundle] refactored the built-in web server
[FrameworkBundle] fixed edge cases for translation:debug and tweaked the output
feature #10368 [FrameworkBundle] Added a translation:debug command (fabpot)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[FrameworkBundle] Added a translation:debug command

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

This PR is based on #10076 but fixes a bunch of issues for edge cases. It also uses the new Table helper.

Original description:

This pull request adds a `translation:debug` command that can be used to inspect unused / missing messages and compare them with the fallback ones (for example to detect copy pasted strings). This is inspired by this ruby project https://github.com/glebm/i18n-tasks

Example of output:

![image](https://f.cloud.github.com/assets/47313/2311673/84ae301c-a2f3-11e3-8bf6-96034369e46c.png)

Commits
-------

f039bde [FrameworkBundle] fixed edge cases for translation:debug and tweaked the output
597a310 Added a translation:debug command
Add tests for RequestStack class
minor #10326 [HttpFoundation][Tests] Add tests for RequestStack class (inalgnu)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10326).

Discussion
----------

[HttpFoundation][Tests] Add tests for RequestStack class

| 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

Commits
-------

6f25d39 [HttpFoundation][Tests] Add tests for RequestStack class
add expression request matcher tests
minor #10322 [HttpFoundation][Tests] Add expression request matcher tests (inalgnu)

This PR was submitted for the 2.4-dev branch but it was merged into the 2.4 branch instead (closes #10322).

Discussion
----------

[HttpFoundation][Tests] Add expression request matcher tests

| 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

Commits
-------

76fe21d [HttpFoundation][Tests] add expression request matcher tests
feature #9852 [Translation] Added template for relative file paths in FileDumper (florianv)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[Translation] Added template for relative file paths in FileDumper

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | https://github.com/symfony/symfony/issues/9845
| License       | MIT
| Doc PR        |

Added ability to support templates for relative paths to translation files.
The file dumpers will try to create the directories if not existing.
Also made `IcuResFileDumper` extending `FileDumper`.

Commits
-------

a04175e Changed placeholders
623d149 Added a ConcreteDumper
84f0902 [Translation] Added template for relative file paths
fixed CS
feature #9739 [FrameworkBundle] Extract KernelTestCase from WebTestCase (johnkary)

This PR was merged into the 2.5-dev branch.

Discussion
----------

[FrameworkBundle] Extract KernelTestCase from WebTestCase

| Q             | A
| ------------- | ---
| Bug fix?      | No
| New feature?  | Yes
| BC breaks?    | No
| Deprecations? | No
| Tests pass?   | Yes
| Fixed tickets | None
| License       | MIT
| Doc PR        | symfony/symfony-docs#3311

Previous discussion is in #7704. Opened new PR to target master branch.

This idea came to me while reading the Cookbook article [How to create a Console Command - Testing Commands](http://symfony.com/doc/master/cookbook/console/console_command.html#testing-commands) and I wanted to hear feedback from others before submitting a patch.

Basically the Cookbook article states that when testing a Command that extending `WebTestCase` is a good way to get access to the Kernel and thus the Container. This struck me as weird because I was wanting to test a Command, which doesn't really have anything to do with "the web."

Currently `WebTestCase` doesn't do anything internally that looks like web-specific work, and the class docblock itself states "WebTestCase is the base class for functional tests.".

After a suggestion in #7704 by @beberlei, I decided to take his advice and now have the following implementation:

Extracted a new class `KernelTestCase` from `WebTestCase` and instead allow WebTestCase to extend KernelTestCase. Pulled all methods up into KernelTestCase except `createClient()` because `createClient()` is focused solely on creating a Client for issuing web-based requests.

Benjamin's solution provides us a clear extension point from `KernelTestCase` for Command-based tests and also provides 100% backwards-compatibility without the need to deprecate WebTestCase.

Commits
-------

c4f14fb Extract new base test class KernelTestClass
fixed previous merge
[HttpKernel] fixed unit tests when using phpunit.phar