Fixed predis recipe dependency to work for all PHP versions/platforms.

The dependency on 'php5-dev' was hard-coded into the predis recipe, but that doesn't work in all cases (I'm using PHP 5.3 IUS on CentOS 6.4 for example). The module_dev recipe already determines the right package for each platform, so it can use that instead.
Merge pull request #31 from brism/predis-fix

Fixed predis recipe dependency to work for all PHP versions/platforms.