[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
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[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
[FrameworkBundle] refactored the built-in web server