feat(composer): require PHP 5.3.29 (PHP 5.3.x EOL version) minimum

[bighappyface]

With PHP 5.3.x EOL as of 8/14/2014 it is time to remove support for PHP 5.3.x versions prior to the last version.

https://secure.php.net/releases/5_3_29.php

[stof]

given that composer defines the platform php version to 5.3.9 (its min version), it means it will never use 1.6.1+ versions and so won't have bugfixes.
So I suggest reverting the requirement change (there is nothing actually incompatible with older PHP versions in the library AFAICT)

[bighappyface]

Hey folks,

PHP 5.3 is long gone and anything less than 5.3.30 isn't recommended for anyone.

Considering that you, the users, are consuming this package on older platforms, I recommend simply skipping the platform requirements during install:

http://stackoverflow.com/questions/26165101/skip-composer-php-requirement

[stof]

@bighappyface I'm talking about the building of the Composer dependencies themselves, which target the older version.
and the composer requirement is not about a recommended version. It is about a required version. Most projects I maintained are compatible with 5.3+ or 5.4+, but the recommended version is still to use the latest (I would recommend 5.6 or 7 for now, at the latest patch version of course).

[bighappyface]

@stof Checkout #231

We are good to go.