Enhancement: Support file and directory exclusions in putRecursive and getRecursive

Please note that this is my first contribution to a PEAR package, so I will need some guidance on best practices, etc.

With this change, one can supply a list of excluded file and directory paths to the putRecursive and getRecursive functions. Backwards compatibility is preserved as the excluded_paths array is empty by default.

Test results:

phpunit tests
PHPUnit 3.7.8 by Sebastian Bergmann.

SSSSSSSSSSSS

Time: 0 seconds, Memory: 6.75Mb

OK, but incomplete or skipped tests!
Tests: 12, Assertions: 0, Skipped: 12.