Put version into quotes, otherwise it fails

When using the `zsh` shell, the command fails because of:

```
$ composer create-project symfony/framework-standard-edition myproject/ ~2.5
zsh: no such user or named directory: 2.5
```

This problem does not occur in Bash.
Quoting the version number does not effect Bash, and fixes ZSH.
minor #4091 Put version into quotes, otherwise it fails in ZSH (dannykopping)

This PR was merged into the 2.5 branch.

Discussion
----------

Put version into quotes, otherwise it fails in ZSH

When using the `zsh` shell, the command fails because of:

```
$ composer create-project symfony/framework-standard-edition myproject/ ~2.5
zsh: no such user or named directory: 2.5
```

This problem does not occur in `bash`.
Quoting the version number does not effect `bash`, and fixes `zsh`.

Commits
-------

6dc62a8 Put version into quotes, otherwise it fails
See #4091
bug #4093 See #4091 (dannykopping)

This PR was submitted for the master branch but it was merged into the 2.3 branch instead (closes #4093).

Discussion
----------

See #4091

Commits
-------

5214cb4 See #4091
Wrapping create-project in strings on different versions
Merge branch '2.3' into 2.4

* 2.3:
  Wrapping create-project in strings on different versions
  See #4091

Conflicts:
	book/installation.rst
Merge branch '2.4' into 2.5

* 2.4:
  Wrapping create-project in strings on different versions
  See #4091

Conflicts:
	book/installation.rst
	quick_tour/the_big_picture.rst
Merge branch '2.5'

* 2.5:
  Wrapping create-project in strings on different versions
  See #4091
  Put version into quotes, otherwise it fails

Conflicts:
	book/installation.rst