Rewritten most of the cache configuration handler.

To ease unit testing with mocks the methods that rely on file paths have been
modified to rely on a SplFileInfo object.
Migrated the cache configuration handler tests to PHPUnit.
Added utility classes for file and filesystem management.
Documentation for the file utility.
Updates to the cache configuration handler.
Migrated unit tests for the cache configuration handler to PHPUnit.
Migrated the configuration unit tests to PHPUnit.
Minor code style adjustments.
Renamed the test bootstrap file.
Removed the SimpleTest library, migrating to PHPUnit.