Update testing/index.md for clearer PHPUnit installation instructions

Step by step Composer installation instructions, including a composer.json example.
In addition:
- Removed self-page reference to introduction
- Noted End of Life for PEAR Installation Method
- Removed reference to Ruby as this doesn't add value
- Shortened testing via Web Browser section (as covered in Composer installation instructions)
Re: docs/en/topics/testing/index.md
Have updated the Pull Request as advised with three additional commits.
Please advise on next steps.
Thanks

On 8/09/2014, at 11:03 pm, Ingo Schommer <notifications@github.com> wrote:

> In docs/en/topics/testing/index.md:
> 
> >  
> >  	composer update --dev
> >  
> >  This will install (among other things) the [PHPUnit](http://www.phpunit.de/) dependency, which is the framework we're
> >  building our unit tests on. Composer installs it alongside the required PHP classes into the `vendor/bin/` directory.
> > -You can either use it through its full path (`vendor/bin/phpunit`), or symlink it into the root directory of your website:
> > +
> > +Open a browser at `http://localhost/dev/tests` to see a list of available tests.  Run a test to ensure the installation is complete. 
> > +
> > +#### An Option
> > +You can either use PHPUnit through its full path (`vendor/bin/phpunit`), or symlink it into the root directory of your website:
> >  
> >  	ln -s vendor/bin/phpunit phpunit
> >  
> >  ### Via PEAR
> I would say we just remove that as a documented option, not much point keeping it given how heavily we push for composer in other places.
> 
> —
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