clean handling of :: passed to find()

Commands cannot have a double colon in their name (for example, a
command can't be named `foo::bar`). However, one might try to
retrieve a `foo::bar` command from the application like this:

```php
$command = $application->find('foo::bar');
```

The `findAlternatives()` method of the `Application` class fails to
handle these strings when there are commands registered with a name
consisting of at least three parts (e.g. a command is named
`foo:bar:baz`). In this case, an empty string is passed to `strpos()`
causing PHP to raise a warning.
[Console] add a dot
Merge branch '2.3' into 2.5

* 2.3:
  [FrameworkBundle] minor fix
  [Console] add a dot
  [Form] remove unnecessary call

Conflicts:
	src/Symfony/Component/Console/Tests/Fixtures/application_1.json
	src/Symfony/Component/Console/Tests/Fixtures/application_2.json
Merge branch '2.5'

* 2.5:
  [FrameworkBundle] minor fix
  [Console] add a dot
  [Form] remove unnecessary call
  clean handling of :: passed to find()

Conflicts:
	src/Symfony/Bundle/FrameworkBundle/Controller/ControllerNameParser.php
	src/Symfony/Component/Console/Tests/Fixtures/application_1.txt
	src/Symfony/Component/Console/Tests/Fixtures/application_2.txt
	src/Symfony/Component/Console/Tests/Fixtures/application_astext1.txt
	src/Symfony/Component/Console/Tests/Fixtures/application_astext2.txt
	src/Symfony/Component/Console/Tests/Fixtures/application_gethelp.txt
	src/Symfony/Component/Console/Tests/Fixtures/application_run1.txt