Add unit tests

As discussed on IRC, here are some tests written with atoum. 
I will continue to cover Pickle source code.

Build status: [![Build Status](https://travis-ci.org/jubianchi/pickle.svg?branch=atoum-tests)](https://travis-ci.org/jubianchi/pickle)
Ah it should be the one not released yet. Good catch :)
On Jun 16, 2014 10:19 AM, "Julien BIANCHI" <notifications@github.com> wrote:

> In src/PackageXmlParser.php:
>
> > @@ -31,6 +41,12 @@ public function parse()
> >              throw new \Exception('Only extension packages are supported');
> >          }
> >
> > +        echo "Packager Version: " . $sx['packagerversion'] . "\n";
> > +        echo "XML Version: " . $sx['version'] . "\n";
> > +        echo "Extension pkg: " . $sx->providesextension . "\n";
> > +        echo "Package name: " . $sx->name . "\n";
> > +        echo "Package version: " . $sx->version->release . "\n";
>
> @pierrejoye <https://github.com/pierrejoye> as far as I understand,
> $sx->version->release points to the current release (not released yet)
> and $sx->changelog->release->version->release points to the last release
> in the changelog (the last released one).
>
> I don't know if we can consider the release in /version/release as being
> a stable release and show its value as the package current version or if we
> should use the last one in the changelog.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/pierrejoye/pickle/pull/6/files#r13795092>.
>