Pear enhancements

I've ran into some issues creating packages for the default debian php setup, so I've added options for these customizations.

Some junk was left in some pear packages, I've added those directories to the list to be deleted from staging.

Then there's the case of task:replace in pear installer, which is used to replace tokens in php files with pear config values. This is used to insert the pear directory in the executable files, I've added a workaround for this issue too. (See [PHPUnit](https://github.com/sebastianbergmann/phpunit/blob/master/package.xml#L209) for example)