Fix version validation rule to use full-matching
bug #6 Fix version validation rule to use full-matching (fivestar)

This PR was squashed before being merged into the 1.0-dev branch (closes #6).

Discussion
----------

Fix version validation rule to use full-matching

Currently:

```
% symfony new blog/ a2.2.5

 Downloading Symfony...

  [GuzzleHttp\Exception\ClientException]
  Client error response [url] http://get.symfony.com/Symfony_Standard_Vendors_a2.2.5.zip [status code] 403 [reason phrase] Forbidden

new name [version]
```

After fixed:

```
% symfony new blog/ a2.2.5

  [RuntimeException]
  The Symfony version should be 2.N.M, where N = 0..9 and M = 0..99

new name [version]
```

Commits
-------

b0d17a8 Fix version validation rule to use full-matching