Fix install_packge, so version is correctly used.

This is a fix so pear version provided are correctly used on installation.
https://tickets.opscode.com/browse/COOK-4319

For example The resulting command was:
> pear -d preferred_state=stable install -a PHP_CodeSniffer -1.5.1
But should be:
>pear -d preferred_state=stable install -a PHP_CodeSniffer-1.5.1