Tidy up PHP code examples in readme

[rowanhill]

Hi,

Just spotted this library after considering writing something similar myself - looks neat! I haven't had a chance to try it out yet, but I'm looking forward to it.

I just noticed that the PHP code examples in the readme could do with a little love, and since it was so quick to do I thought I'd submit a PR right here and now.

Changes are fairly obvious, but to be explicit, I have:

• Added PHP syntax highlighting
• Added missing 'function' keywords
• Referenced $family instead of the undefined variable $parent (which I assume was the original intent?)
• Made the spacing consistent (no newlines at the start of classes or functions)

Thanks!
Rowan

[balihoo-cdamour]

thx for the fixes, these apply to https://github.com/balihoo/phockito-unit-php-di too!