Allow script who dont starts by <?php
minor #34 Allow script who dont starts with <?php (jeremy-derusse)

This PR was merged into the master branch.

Discussion
----------

Allow script who dont starts with <?php

The main purpose, is to allow a shebang as in the follwing script

```
#!/usr/local/bin/melody run
<?php

<<<CONFIG
packages:
    - "twig/twig: ~1.0"
CONFIG;

$loader = new Twig_Loader_Array(array(
    'index' => "Hello {{ name }}!\n",
));

$twig = new Twig_Environment($loader);
echo $twig->render('index', array('name' => 'Melody'));
```

Commits
-------

f0c5248 Allow script who dont starts by <?php
Ask confirmation for untrsuted resources
Ask for displaying the resource
Store trusted signatures in a melody config file
Add documentation
Add tests
Fix typo
Take feedback into account
Simplify UserConfiguration